LEWISTON — Fire investigators have ruled that an explosion at a commercial garage on Sabattus Street last week was an accident caused by a liquid propane leak.

The Friday morning blast at Rotary Auto Sales at 865 Sabattus St. sent two workers to the hospital. One of them, Ryan Bouchard of Lewiston, suffered second degree burns to his face and arms in the blast and was taken to a Portland hospital.

Lewiston fire investigators were joined by the Office of State Fire Marshal in their search for the cause of the blast. After concluding their probe Monday, it was disclosed that liquid propane gas had been leaking from an abandoned gas line in a wall.

A Lewiston firefighter shuts down his line Friday at the rear of Rotary Auto Sales on Sabattus Street. The back wall was blown out from a liquid propane leak, investigators said Monday. Russ Dillingham/Sun Journal

Bouchard had been doing grinding work beneath a truck when sparks apparently ignited the gas and cause the explosion about 11:35 a.m., according to a family friend. The explosion blew out a wall of the building, which stands at Sabattus Street and Randall Road.

The victim’s brother later said that Bouchard is expected to fully recover from his injuries.

Rotary Auto Sales has been closed since the blast while officials there search for another location. It is believed the building had not been equipped with a gas detector, as required by law since the start of the year.