ARLINGTON (CBSDFW.COM) - Firefighters are investigating what started an apartment complex fire that affected 10 different units.

Darrel Whitfield from the Arlington Fire Department says the fire was reported around midnight at the Spanish Park Apartments.

When firefighters arrived at the scene they determined they would need additional assistance. During a 30 minute period it escalated into a three alarm fire.

One firefighter was taken to the hospital for heat exhaustion. No other injuries have been reported.

Ten units were damaged by the fire but only eight of them are occupied.

About a dozen people have been displaced from the fire. The Red Cross and apartment management are looking for potential housing.