Arkansas City police are investigating the death of a 2-year-old boy who was found unresponsive at an apartment over the weekend.

The police say in a news release that Manton Kieffer died Sunday at an Arkansas City hospital.

When officers and emergency medical personnel arrived at the Garden Walk Apartments, they found neighbors performing CPR on the child. Police say the boy apparently was being cared for by the mother’s boyfriend.

The cause of death has not been determined.