Uganda's President Yoweri Museveni on Sunday ordered more troops to western Uganda where attackers from a group with links to Islamic State killed at least 37 secondary school students.
Members of the rebel Allied Democratic Forces (ADF) killed the students late on Friday at Lhubirira Secondary School in Mpondwe, near the border with the Democratic Republic of Congo.
Military and police said the attackers had also abducted six students and fled towards the Virunga National Park across the border. Their fate is unknown.
Museveni said more soldiers had joined the pursuit in the area, which includes Rwenzori Mountain, from where the ADF launched their insurgency against Museveni in the 1990s.
"We are now sending more troops into the area south of Rwenzori Mountain," he said in a statement.
"Their action, the desperate, cowardly, terrorist action, therefore, will not save them. We are bringing new forces to the Uganda side as we continue the hunting on the Congo side."
Discrepancy in number of reported deaths
On Saturday, privately owned NTV Uganda television said the death toll stood at 41, while the state-run New Vision newspaper said it was 42. New Vision said 39 of the dead were students, and some were killed when the attackers set off a bomb as they fled.
The attack drew widespread international condemnation including from the United Nations, the African Union and East Africa's Intergovernmental Authority on Development. Ugandans were shocked by the attack.
"Parents across the country, please do not panic, our children are safe, and they will remain safe. They are evil people and they are trying to harm our children, but they will not manage," Janet Museveni, the First Lady and Education Minister, said late on Saturday.
Museveni said the government would also investigate if there were any lapses that enabled the attack to happen.
"Was an alarm sounded and by whom? How did the nearby security people respond? Why didn’t our people on the Congo side have intelligence on this splinter group etc?" Museveni said.
The ADF was largely defeated by the Ugandan military but remnants fled into the vast jungles of eastern Congo from where they have since maintained their insurgency - attacking civilian and military targets in Congo and Uganda.
In April, the ADF attacked a village in eastern Democratic Republic of Congo, killing at least 20 people.