The cause of the blast on Thrush Avenue shortly after 10 p.m. local time (11 p.m. ET) has not been determined, but natural gas was cut off to the home, which was leveled by the explosion and caught fire, a spokesman for the St. Louis Fire Department said.
Two men were trapped in the wreckage but freed by firefighters, the fire department said. They were taken to an area hospital and were in critical condition, but stable late Thursday.
Two neighboring houses were set on fire after the two-story house exploded, firefighters told NBC station KSDK. The St. Louis County Bomb and Arson Squad was investigating the scene, the fire department said.
An active scene. *3rd Alarm* Home Explosion 700blk of Thrush. Two trapped; one #rescued..Still actively firefighting pic.twitter.com/tygL96wqot
— STLFD PIO (@STLFireDept) July 17, 2015