New Orleans firefighters encountered heavy fire and smoke conditions Monday afternoon at a former elementary school.
The fire would eventually go to three alarms as additional crews were needed to assist at the building that was being converted into housing.
Welding contractors said they had accidentally set fire to the structure while attempting to cut steel beams in the ceiling, officials said in a release.
The operation was described as exhausting as firefighters had to force entry through multiple doors and windows to both extinguish the fire and search for persons possibly trapped inside.
There were no injuries.