Fire officials say the blaze broke out after 9:00 a.m. in the 6800 block of Vandike Street.
It took crews about half an hour to get the upper hand.
Medics took a 44-year-old man to Aria-Torresdale Hospital with burns to his face, arm and legs. He is listed in critical condition.
Authorities say an initial investigation indicated that something thrown at the property may have caused the small explosion.
Police and fire officials continue to investigate.