An Arvada police officer was shot Thursday evening by a fellow officer while responding to a call, officials said.

Officers responded to a report of a person down at a house in the 6400 block of West 60th Avenue in Arvada at about 6:20 p.m., said Dave Snelling, a spokesperson for the Arvada Police Department.

One officer located the person suffering from a medical emergency, when a second officer saw “what he perceived as a threat, fired a round and struck the other officer,” Snelling said.

Police did not say where the bullet struck the officer, but said he suffered “very minor injuries” and was released from the hospital hours later.

An internal investigation into the incident is underway.