Firefighters believe a squatter started the fire in a vacant Tulsa building early Tuesday trying to keep warm and it got out of control.
The Tulsa Fire Department was called to the 800 block of South Rockford just before 6:45 a.m. They arrived to find smoke pouring from the building.
Firefighters say a boarded up doorway inside the building appeared to have been kicked in.
After a search, firefighters say no one was found inside the building.