AP — A man killed four children in a machete attack inside a nursery school in the Ugandan capital of Kampala on Thursday, according to police.

The man gained access to the Gaba Early Childhood Development Program in Kampala and attacked an “unspecified number of children with a sharp object,” according to the local Daily Monitor newspaper.

“Eyewitnesses say the suspect disguised himself as a parent and first entered the school offices, where he briefly engaged the administrator in charge,” it reported. “He later stepped outside, locked the gate, and began attacking the children one after another.”

Police spokesman Kituuma Rusoke said at least four children were killed in the attack. He said the motive was unknown. The suspect has since been arrested.

This kind of attack is rare in Kampala, a city of roughly 3 million people.