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CHICAGO — A police shooting on the Northwest Side Tuesday morning involved Chicago Police officers assigned to Mayor Lori Lightfoot’s security detail, sources told WGN Investigates.

No one was injured in the shooting, which occurred shortly after 7 a.m. in the 1800 block of North Monticello.

Police sources said the officers witnessed an attempted robbery, and then exchanged gunfire with the robbery suspects. It was not immediately clear who fired first, and none of the suspects were in custody Tuesday morning.

In a statement issued Tuesday morning, the CPD said that no weapons were recovered at the scene.

The Civilian Office of Police Accountability has opened an investigation into the shooting, and the involved officers will be placed on administrative duty for 30 days, according to police.