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

The man gained access to the Gaba Early Childhood Development Program in Kampala by disguising himself as a parent, the Daily Monitor newspaper reported.

He first entered the school offices, where he briefly engaged the administrator in charge, then stepped outside, locked the gate and began attacking the children, the report said.

The attacker “brutally stabbed and killed four juveniles,” police said in a statement.

The full statement read: “Four Juveniles Killed, Suspect Arrested. We confirm a tragic incident at the Ggaba Early Childhood Development Program school, in Makindye Division Kampala City where a male suspect brutally stabbed and killed four juveniles.The suspect has been apprehended, and the motive behind the killings is still under investigation.”

Video footage aired by local broadcaster NTV showed some parents weeping. Police fired in the air to disperse an angry crowd that gathered near the school, apparently trying to lynch the suspect.

The suspect later was taken into custody, police spokesman Kituuma Rusoke told The Associated Press. A motive for the attack is unknown, he said. Such attacks on children are rare in Kampala, a city of roughly 3 million people.