Twenty-nine-year-old Makasan Halee sits cross-legged on the bare concrete floor of his family home and vows vengeance against his father's killers. "I am so angry now that I will kill to defend my family and my faith," says Makasan. "I want revenge." Crowded around him in the front room of his modest house last Thursday are a couple of dozen grieving, enraged relatives and friends. Along with several hundred other impoverished rubber tappers, Makasan lives in Som, a dusty village situated in Pattani province in Thailand's deep south. The villagers are mourning the loss of Makasan's 63-year-old father, Mae Ai Halee, whom they buried just 12 hours previously in a nearby rubber plantation, his face and hands contorted from the pain of his death, his groin and chest riddled with bullets.

Two days earlier, Makasan had watched his father pack a clean shirt, two sarongs and his prayer beads in preparation for what Mae Ai told him would be a pilgrimage to an ancient and holy mosque in the nearby town of Pattani. The next night Makasan found himself lining up outside the Thai military headquarters in Pattani to collect his father's corpse. Military officials described to Makasan how, together with 31 other men, six of them from Som, his father attacked a police checkpoint, killed two officers, then retreated inside the crumbling, red brick Krue Se mosque to launch a defiant stand against the might of the Thai military. When the automatic-weapon fire had ceased and the tear gas had cleared nine hours after the siege began, all 32 lay dead, their bodies lying in bloodied heaps on the stone floor of the mosque. It was not the only blood spilled that day. In an unprecedented outbreak of carnage that has stunned this predominantly Buddhist nation, 108 Muslims were killed after a series of apparently coordinated attacks on police posts and government installations across three provinces in the south. Five members of the security forces also died.

Eyewitnesses describe Makasan's father as the emir, or head, of the group that took over the mosque. But Makasan and his fellow villagers refuse to believe that Mae Ai was the leader of the Krue Se militants. The Mae Ai they knew couldn't be the same man who, it is suspected, initiated the killings by slashing to death an unsuspecting policeman with a machete. "My father just went to the mosque to pray," Makasan says, barely able to contain his fury. "He was a good Muslim, and the Thai army killed him."

With scores of other sons, brothers and fathers likewise vowing revenge, Thailand's south, home to most of the nation's 6 million Muslim minority, is again a powder keg ready to explode. The south is the country's poorest region and was once wracked by a guerrilla insurgency agitating to set up an independent Islamic state. The militants, who often hid in neighboring Malaysia, were not widely supported, but their cause reflected the resentment and sense of marginalization that many Thai Muslims felt. The movement waned in the 1980s and '90s as the authorities in Bangkok boosted economic aid to the south, gave it some autonomy and pardoned many insurgents. And though there had been a steadily rising tide of killings and attacks on security posts in the south in recent years, most officials and analysts dismissed the unrest as sporadic and low-level, blaming bandits as much as they did separatists, until last week's bloodbath. Now the scale and ferocity of the April 28 violence is forcing Thais to confront the reality that Islamic militancy in the south has escalated into a national crisis. The morning after the killings, "Thais woke up to a new reality," editorialized Bangkok's The Nation newspaper. "What happened... may change Thailand forever."

The most profound and dangerous fallout is the potential internationalization of what had previously been a local problem. The image of non-Muslim security personnel firing rocket-propelled grenades and M-16s as they storm the most sacred mosque in Pattani province could serve as a rousing recruitment ad for Islamic radicals worldwide to join the jihad in Thailand. "There's a real danger that militants from Malaysia, Indonesia or the Arab world will now become involved in Thailand's internal conflict," says Anusorn Limmanee, a political scientist at Chulalongkorn University in Bangkok. Any involvement by outside extremists would also raise another grim specter: the possibility that the militants might turn their sights on the millions of foreigners who flock to Thailand's beach resorts, dealing a body blow to the country's chief source of foreign currency, its $7 billion-a-year tourism industry. Ominously, one Islamic separatist group that had been quiet for decades, the Pattani United Liberation Organization (P.U.L.O.), published a warning to foreign tourists on its website within 24 hours of the killings. The message, addressed to "Dear People of the World," said: "Persons who plan to visit Thailand NOW are warned not to travel to Pattani ... Pattani people are not responsible for what happens to you after this warning." The notice pointedly includes the tourist havens of Phuket and Krabi, a few hours' drive away. Already, the U.S., Britain, Australia, New Zealand and Malaysia have advised their citizens to avoid Thailand's south.

Any escalation of violence will depend, of course, on the leadership, organizational ability and funding of the handful of small separatist groups in the south. But even the most basic information about these groups, the size of their memberships, how much they cooperate with one another, what links they have to international militant Islamic groups such as al-Qaeda and Jemaah Islamiah (JI), remains largely a mystery. "Most of the groups have been dormant for years," says a Malaysian intelligence official in Kuala Lumpur, so they have largely fallen off the radar. But, he adds, while relatively few in numbers, the militants have remained active. "They were waiting for the right time, doing their networking. Based on ground reports, we believe the various groups have now come together to forge a stronger alliance against the Thai government." The best indication of this is the increasingly frightening trail of destruction the south has witnessed lately: since the start of the year, some 70 security personnel, teachers, Buddhist monks and other non-Muslims have been killed; hundreds of automatic rifles and nearly a ton of explosives have been stolen; and scores of government buildings, including schools, have been burned down apparently for teaching Thai language and culture (the Muslims traditionally speak Malay). "It is clearly recognizable that these groups are in the early stages of arming themselves and training," says Rohan Gunaratna, a Singapore-based expert on terrorism. "There is much more bloodshed to come."

A succession of events has combined to breathe new life into the dying embers of the southern Muslims' separatist cause. First came the 9/11 attacks in the U.S. and the accompanying global revival of radical, jihadist Islam, fueled by the U.S.-led wars in Afghanistan and Iraq. Coupled with that was a crackdown in Malaysia that saw many militants fleeing back across the notoriously porous border into southern Thailand. But the biggest factor, say critics of Thai Prime Minister Thaksin Shinawatra, has been the central government's hardball approach to the south since he came to power.

A policeman before becoming a businessman and a politician, Thaksin is trying to play both good and bad cop. He has repeatedly pledged to divert more development funds to the south. But he also declared martial law in the area immediately after a Jan. 4 raid on a Thai army base there, ordered more troops to the region, and abandoned a program that emphasized cooperation between the military, the police and community leaders. Instead, Thaksin gave sole responsibility for public security to the police, who are reviled by the Muslims because they consider the cops corrupt and insensitive to Islamic customs. Widespread arrests and mysterious disappearances soon followed. One notorious case was the recent and still unsolved disappearance of Somchai Neelahphaijit, a Muslim lawyer who was defending four men accused of membership in JI. Four policemen have been detained as suspects in his disappearance, but no charges have been filed. In recent months, says Kraisak Choonhavan, head of the Senate committee on foreign affairs: "The police have arrested a lot of highly respected [Muslim] people in the community. That really feeds anger and resentment against the government." Vairoj Phiphipakdee, an opposition lawmaker and Muslim from Pattani who has met with gangs that have shot policemen and burned schools, says he has observed a marked change in the separatist cause over the past two years. Back then, he estimates, there were fewer than 20 hard-core separatists in the south. Now, he says, "I believe it's a full-blown separatist revolt involving hundreds of people and it came about because of mistakes in government policy."

Domestically, Thaksin's tough stance in the south has seemed to draw support from many non-Muslim Thais. His approach has certainly worked in other problem areas: opinion polls showed widespread backing for his recent antinarcotics campaign that saw more than 3,000 alleged drug dealers killed, many of them in unexplained circumstances. But none of this has helped Thailand's international reputation, says Sunai Phasuk of Human Rights Watch in Bangkok: "Thailand is now a country that has a problem with terrorism. Thailand is now a country that has a problem with treatment of religious minorities. Thailand is now a country that has a problem with the rule of law and human rights. That's the new image of Thailand."

Baba Lukman personifies the south's rage against Bangkok. A slightly built man in his 50s, he is a self-confessed separatist fighter who leads a cell of militants aligned to a group calling itself New P.U.L.O. (According to Andrew Tan, a regional security expert at Singapore's Nanyang Technological University, New P.U.L.O. is one of six main groups that have recently pooled their resources under a single banner, Bersatu, the Malay word for united.) In what is a rare interview with a southern Thai militant, Time met with Lukman a few days prior to the April 28 bloodbath in a dimly lit room upstairs from a garbage-strewn alley in the Thai town of Sungai Golok, which borders Malaysia. Lukman, who insisted on conducting the interview at 3 a.m. for security reasons, says his group was responsible for the January raid on the army depot and also the torching of several government schools that month. His organization's goal: an independent Islamic state in Thailand's south. "We cannot compromise," he says, his voice muffled by the red-and-white check scarf covering most of his face. "The Thai government is not interested in talking to us. The fight will go on. We want independence. Nothing less than that."

Lukman, whose eyelids are outlined with a traditional makeup paste called kohl, a practice favored by some devout male Muslims, blames what he says is the brutality of the police and military for the upsurge of violent attacks by militants. "The Pattani people want to live in peace but Thaksin's government is arrogant. Most atrocities are carried out by the Thai government officials and they put the blame on us. When an attack or bomb blast happens, everyone thinks it's done by the freedom fighters." He adds bitterly: "Why are you reporters not writing about the hundreds of people who go missing from all the Muslim provinces?"

If the Thai government needs any further explanation for why men like Lukman are attracting an increasing number of recruits, it need only look at the village of Som. Last week, on the day of the killings, the Muslim residents gathered at the mosque and watched stone-faced as their dead, nine in total, six from the Krue Se mosque and three who allegedly raided a checkpoint in Mae Lan, returned in the back of pickup trucks. The corpses, wrapped in bloodstained sheets, were laid out on the tiled floor at the mosque entrance to be readied for burial. The villagers crowded the forecourt to watch as the sheets were lifted one by one to reveal the bullet-riddled bodies. While children as young as six years old looked on, female relatives kneeled and gently kissed the bloodied foreheads of their dead. Among the menfolk, the talk was of how these deaths were further proof of the brutality of the security forces. Surveying the corpses, village preacher Abdul Romae says, "These men are innocent, just like our Muslim brothers being killed in Iraq." For Makasan, the rubber tapper whose father was among those who died on April 28, his duty seems clear: "I am ready to kill."