MPONDWE: Militants linked to the Islamic State group massacred at least 37 people and abducted six others in western Uganda, the army said Saturday, in the country's worst such attack in years.

The military said it was pursuing the attackers from the Allied Democratic Forces (ADF) after they raided a school late Friday near the border of the Democratic Republic of Congo.

Officials said dormitories were locked and set alight and students cut down with knives in a grisly late-night assault on Lhubiriha Secondary School in Mpondwe.

Police and army officials blamed the ADF, one of the deadliest militias over the border in DR Congo's strife-torn east, which the Islamic State group has called its local offshoot.

"Unfortunately, 37 bodies have been discovered and conveyed to Bwera hospital mortuary," Uganda Peoples' Defence Forces (UPDF) spokesman Felix Kulayigye said in a statement, referring to a town near the attack.

He said eight people were injured and six others kidnapped and taken toward Virunga National Park, a vast expanse which straddles the border.

"UPDF embarked on pursuing the perpetrators to rescue the abducted students."

Joe Walusimbi, resident commissioner for the district of Kasese where the attack occurred, earlier told AFP that at least 25 of the deceased were students at the school.

Police have not released details about the victims' ages or how many were students.

Outside the school, heavily-armed soldiers and police stood guard, where a large crowd gathered and distraught survivors were comforted by loved ones.

It is the deadliest attack in Uganda since twin bombings in Kampala in 2010 killed 76 in a strike claimed by the Somalia-based Al-Shabaab group.

'Big attack' 
According to a police report seen by AFP, police and military units were alerted to a "big attack" at the school around 11:00 pm (2000 GMT) on Friday evening.

"On arrival, the school was found burning and the dead bodies of students were found lying in the compound and the school's food store was broken into" with items missing, the report stated.

The school is less than two kilometres (1.2 miles) from the border of DR Congo, where ADF is primarily active and has been accused of killing thousands of civilians since the 1990s.

Major General Dick Olum told AFP that intelligence suggested the presence of the ADF in the area at least two days before the attack, and an investigation would be needed to establish what went wrong.

He said it appeared the attackers had detailed information about the school.

"They knew where the boys and girls' dormitories resided," said Olum from Mpondwe, who has been leading an army operation against the ADF in Uganda and DR Congo.

"This is why the rebels locked the boys' dormitory and set it on fire. The rebels did not lock the girls' section and the girls managed to get out, but they were cut with machetes as they ran for safety, and others were shot".

He said some of the bodies were burned beyond recognition and DNA testing would be required to identify them.

"We have called for more firepower, planes to help in the rescue operation of those abducted, and locating the rebel hideouts for military action," he said.

'Killed brutally' 
The rebels fled toward Virunga on the border with Uganda and Rwanda, a globally renowned sanctuary for rare species including mountain gorillas.

Militias -- of which dozens are active in the mineral-rich eastern DR Congo -- also use the park as a hideout.

Originally made up of mainly Muslim Ugandan rebels, ADF gained a foothold in eastern DR Congo in the 1990s.

Since 2019, some ADF attacks in eastern DR Congo have been claimed by the Islamic State group, which calls the fighters the Islamic State Central Africa Province.

ADF strikes in Uganda are less common and Friday's sent shockwaves through the country.

"They were killed brutally... It is pathetic and regrettable," Vice President Jessica Alupo told a graduation ceremony in Kampala on Saturday.

But Florence Kabugho, an MP for Kasese, told reporters there were "very many unanswered questions" given the heavy military presence so close to the border.

"Where was this security when these killers came to Uganda?" she said.

Uganda and DR Congo launched a joint offensive in 2021 to drive the ADF out of their Congolese strongholds, but the measures have failed to blunt the group's violence.

It is not ADF's first attack on a school in Uganda.

In June 1998, 80 students were burnt to death in their dormitories in an ADF attack on Kichwamba Technical Institute near the Dr Congo border. More than 100 students were abducted.