PHILADELPHIA (WPVI) -- Philadelphia police say someone set fire to a vacant Philadelphia Housing Authority building on Monday morning.
The fire department was called to the PHA property at 20th and Chestnut streets around 9:30 a.m.
They got the flames under control within 30 minutes.
Investigators soon determined the fire was set intentionally.
No other properties were damaged.
Anyone with any information is asked to call police.