HARRIS COUNTY, Texas — Investigators are working to determine the cause of a 2-alarm fire that happened at a north Harris County apartment complex early Sunday morning. 

The complex sits on the intersection of Ella Boulevard and Clear Valley Drive.

About 12 units were destroyed or damaged because of the fire. Fortunately, residents were able to get out safely and no one was injured. 

The Little York Fire Department said the fire was coming through the roof of the top floor units. 

How the fire started is still under investigation. 

The fire took about 45 minutes to an hour to put out, according to firefighters. 

No firefighters were injured.