Firefighters are investigating an apartment complex fire in Pasco that happened early Friday morning. Pasco Firefighters and several others from surrounding agencies responded to the Stonegate Apartments on Road 68 at about 1:30 a.m. The fire started on a bottom-level unit in building J of the complex, according to fire crews on the scene. The fire then spread to the units right above in the second and third floors. Crews evacuated all twelve units in the building. No one was injured. However, the apartment where the fire started is badly damaged. The cause of the fire is under investigation.