Firefighters are trying to determine what caused a two-alarm fire an at the former Valena C. Jones Elementary School in the Seventh Ward Sunday afternoon.

According to the New Orleans Fire Department, firefighters responded to a 911 call just before 5 p.m. at 1901 North Galvez Street. The incident was classified as a two-alarm due to the size of the building and heat index.

Investigators say the fire is believed to have started in the second floor and extended through the third floor into the walls and ceiling. The building was vacant and there were no utilities in service.

The fire was under control one hour after first responders arrived at the scene.

Paramedics treated and released one firefighters for heat exhaustion at the scene.