OKLAHOMA CITY - Firefighters are battling a commercial fire in southwest Oklahoma City.

The fire was reported about 5:30 a.m. Monday in the 1900 block of Exchange Avenue near Pennsylvania Avenue. 

The building was old and vacant for some time. Due to its condition, there was no roof on the building. 

Firefighters think homeless people were living in the building when it caught on fire.

Stay with News 9 and News9.com for more information as it becomes available.