Ugandan authorities have recovered the bodies of 41 people, including 38 students, who were burned, shot or dismembered after suspected rebels attacked a high school near the border with Congo, the local mayor said on Saturday.

At least six people were abducted by rebels who fled across the porous border into Congo after an airstrike on Friday night, the Ugandan military said.

Authorities blamed the massacre at Lhubiriha High School in the border town of Mpondwe on the Allied Democratic Forces, a shadowy extremist group linked to Islamic State that has carried out attacks from bases in volatile eastern Congo for years.

The victims included students, a guard and two members of the local community who were killed outside the school, Mpondwe-Lhubiriha Mayor Selevest Mapoze told the AP.

Mapoze said some of the students suffered fatal burns when the rebels set fire to the dormitory and others were shot or hacked with machetes.

About five attackers took part in the raid, which took place around 11:30 p.m., the Ugandan military said. Soldiers from a nearby brigade who responded to the attack found the school in flames, “with the dead bodies of students lying on the premises,” said military spokesman Brig. Felix Kulayigye said in a statement.

The statement cited 47 bodies, with another eight people injured and being treated at a local hospital. Ugandan soldiers are “pursuing the perpetrators to rescue kidnapped students” who were forced to carry looted food to Congo’s Virunga National Park, the agency said.

The school, communal and privately owned, is located in Uganda’s Kasese District, about 2 kilometers (1.2 mi) from the Congolese border.

Joe Walusimbi, an official representing the Ugandan president in Kasese, told the AP by phone that some of the victims “were burned beyond recognition.”

Winnie Kiiza, an influential political leader and former MP from the region, condemned the “cowardly attack” on Twitter. She said “attacks on schools are unacceptable and a serious violation of children’s rights”, adding that schools should always be “a safe place for every student”.

The ADF has been blamed for numerous attacks in recent years targeting civilians in remote parts of eastern Congo. They rarely claim responsibility for attacks.

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

The group was founded in the early 1990s by some Ugandan Muslims who said they had been sidelined by Museveni’s policies. In that time, rebels have carried out deadly attacks in Ugandan villages and the capital, including an attack in 1998 that massacred 80 students in a town not from the site of the last attack.

A Ugandan military offensive later forced the ADF into eastern Congo, where many rebel groups are able to operate because the central government has limited control there.

The group has since established ties with the Islamic State.

In March at least 19 people were killed in the Congo suspected ADF extremists.

For years, Ugandan authorities have promised to track down ADF militants outside Ugandan territory. in 2021 Uganda launched joint air and artillery strikes in the Congo against the group.