Smoke and flames inside vacant school in North Philadelphia

NORTH PHILADELPHIA (WPVI) -- Firefighters battled smoke and flames inside a vacant school in North Philadelphia early Thursday morning.

The fire broke out just past 1:00 a.m. on the 1200 block of West Allegheny Avenue.

Crews arrived to find smoke and flames showing on the second floor of a five-story old elementary school building.

They quickly put out the flames and began to ventilate the building.

Investigators are trying to figure out how the blaze started.