A ladder truck in Maryland ran through a red light on the way to a call and hit an SUV, killing three occupants of the SUV.

The ladder was responding to a report of smoke in a building at about 3 a.m. along with several other apparatus. Initial news reports indicate the truck was traveling 47 mph when it went through a red light at an intersection and collided with the other vehicle. Four firefighters were injured in the crash.

Department policy requires apparatus drivers to slow down at red traffic lights, but state law gives them the right-of-way. The accident is under investigation. The smoke was caused by food left on a stove.