Police say a Milwaukee officer has shot and killed a man armed with a knife.

Police say they were called to a residence on the city's northwest side about 8 p.m. Wednesday where a man was threatening suicide. Officers say they ordered the 45-year-old man to drop the knife, but he refused.

A 29-year-old officer with three years on the force shot and killed the man. The officer has been assigned to desk duty.

Police say officers were not injured.