A police officer killed early Friday in the Denver suburb of Lakewood was shot by a fellow officer as several agencies responded to a report of shots fired in a residential area.

James Davies, 35, was in full uniform when he was shot, police spokesman Steve Davis said.

He's the first member of the Lakewood Police Department to be killed in the line of duty since it was founded in 1969. He leaves behind a wife and two children.

"The investigation has taken quite a tragic turn," Davis said. "The words heartbreak and shock are just not adequate when you lose one of your own."

'The words heartbreak and shock are just not adequate when you lose one of your own.' —Steve Davis, police spokesman

Davis said there was a lot of confusion when officers first responded and numerous shots were fired. He said three men were taken into custody and were outside a house when more gunfire erupted and Davies was killed. Multiple agencies responded and officers were warned to avoid crossfire, according to police radio recordings.

Along with Lakewood police, at least four other agencies responded to the initial report, including officers from neighbouring Denver and Edgewater along with Arvada and deputies with the Jefferson County Sheriff's Office.

Some of the officers were in the area investigating a complaint of a prowler.

Davis said there were several pit bulls in the house that complicated the situation.

Davis said handguns were recovered from the home. He did not know if the officer who was killed had fired his weapon.