A D.C. police cruiser and a fire truck were involved in a head-on collision that left two people injured in Northwest on Monday. (WUSA 9)

Authorities are investigating a collision involving a D.C. police cruiser and a fire engine that left two people injured in Northwest Washington.

The cruiser and fire engine crashed in the 2900 block of Porter Street NW around 4:08 p.m., said Officer Sean Hickman, a D.C. police spokesman. Tim Wilson, a D.C. fire department spokesman, said an officer and a firefighter were taken to an area hospital with serious but not life-threatening injuries.

Hickman, who does not know how many people were involved in the crash, said everyone was “conscious and breathing” after the collision. He said it’s not clear what caused the crash or whether the police cruiser and firetruck were responding to the same call.

Wilson said the fire engine was responding to a report of a fire in the 500 block of Kennedy Street NW just before the accident.

D.C. police said Porter Street NW is blocked both ways near the accident site between Connecticut Avenue NW and Rock Creek Park. There is no estimate of when the street will reopen, and authorities recommended that motorists seek alternative routes.