Redlands police officers responded to the shooting in the 1500 block of Lassen Street around 1:50 a.m.
Video shows the fire engine with at least one bullet that pierced through the windshield on the driver's side. Officials say no firefighters were inside of the truck at the time of the shooting.
Authorities say the fire engine was dispatched to a medical aid call, and while crews were inside a home rendering aid, a suspect fired one round at the front windshield of the fire truck.
Police searched the area for the gunman, but no one was taken into custody.
An investigation is ongoing.