KAMPALA, Uganda (AP) — A bereaved Ugandan border town on Sunday prepared to bury victims of a brutal attack by suspected extremist rebels on a school that left 42 dead, most of them students, as security forces stepped up patrols along the frontier with volatile eastern Congo.

One of eight people wounded in Friday night’s attack, in which 38 students were killed, died overnight, said Mpondwe-Lhubiriha Mayor Selevest Mapoze.

“Most of the relatives have come to take their bodies” from the morgue, he said.

Some students were burned beyond recognition, and others were shot or hacked to death after militants armed with guns and machetes attacked Lhubiriha Secondary School, co-ed and privately owned, which is located about 2 kilometres (just over a mile) from the Congo border. Ugandan authorities believe at least six students were abducted, taken as porters back inside Congo.

In addition to the 38 students, the victims include a school guard and three civilians.

UN Secretary-General Antonio Guterres condemned the attack in a statement, urging “the importance of collective efforts, including through enhanced regional partnerships, to tackle cross-border insecurity between (Congo) and Uganda and restore durable peace in the area.”

The atmosphere in Mpondwe-Lhubiriha was tense but calm Sunday as Ugandan security forces roamed the streets outside and near the school, which was protected by a police cordon.

Ugandan security forces have not given a detailed account of how the rebels, active in eastern Congo, were able to carry out the attack. The group, known as the Allied Democratic Forces, or ADF, rarely claims responsibility for attacks. It has established ties with the Islamic State group.

The ADF has been accused of launching many attacks in recent years targeting civilians in remote parts of eastern Congo, including one in March in which 19 people were killed.

The ADF has long opposed the rule of Ugandan President Yoweri Museveni, a U.S. security ally who has held power in this East African country since 1986.

The group was established in the early 1990s by some Ugandan Muslims, who said they had been sidelined by Museveni’s policies. At the time, the rebels staged deadly attacks in Ugandan villages as well as in the capital, including a 1998 attack in which 80 students were massacred in a town not far from Friday’s raid.

The attack followed the same playbook: violence against students. The attackers targeted two dormitories, using extreme force when the boys resisted, according to Ugandan officials.

“This terrorist group couldn’t enter, so they threw in a bomb, they threw in a petrol bomb,” said Education Minister Janet Museveni, who also is Uganda’s first lady. “So, these children were burnt.”

Students have been attacked because schools are considered soft targets, pupils are sometimes recruited into rebels ranks or used to carry food and supplies for insurgents, and such raids provide media coverage coveted by extremists.

The raid appears to have taken Ugandan authorities by surprise, and first responders arrived after the attackers had left.

Some villagers have temporarily moved away from the Mpondwe-Lhubiriha community, fearing more attacks, Mapoze said.

The border is porous, with multiple footpaths not monitored by authorities. Many parts of eastern Congo are lawless, allowing groups like the ADF to operate because the central government in Kinshasa, the capital, has limited authority there.