BENSALEM (AP) — Authorities say a gas explosion in Pennsylvania sent one person to a hospital in critical condition and left another trapped underground.

Emergency responders said the blast happened at about 5 p.m. Tuesday at the Liberty Gas station in Bensalem Township.

The township’s public safety director, Fred Harran, said both victims are believed to be workers. He said one person was trapped under heavy concrete blown apart in the blast.

He said rescue crews were moving the overturned concrete with cranes and were trying to siphon fumes off. Some homes in the area were evacuated as a precaution.

Firefighters from Philadelphia and other surrounding areas responded to the scene.