West Springfield, Ma – A gas explosion in an Elmdale Street apartment building injured a resident and blew a window and frame out into the street Saturday night.

Deputy Fire Chief Daniel Culver said yesterday that the Fire Department received a call at 9:12 p.m. that there was a fire at 53 Elmdale St. Fire apparatus arrived at the scene at 9:15 and found that the front of the attic of the building was already fully involved in fire. Neighbors reported hearing an explosion, and the window was blown out, Culver said.

It appears that the occupant, whose name was not available yesterday, had unwittingly provided the spark that ignited the natural gas in the apartment by turning on an electric light.

Fire Department personnel are still investigating the cause of the gas leak, but it does not appear to be a problem with the gas line itself, Culver said.

The man who lived in the attic apartment was burned and was taken to Baystate Medical Center for treatment by the Agawam Fire Department ambulance, Culver said. One firefighter sustained minor injuries to an elbow.

The explosion bowed the roof of the building and blew slate tiles off the roof.

Firefighters knocked down the blaze from outside, then entered the building to continue fighting the fire, Culver said. Culver could not estimate the damage done by the fire because of the extensive damage to the roof of the structure.

The first floor was vacant at the time of the fire. An unknown number of occupants of the second floor were unharmed, but cannot return to the apartment.

Building Inspector Thomas A. Lagodich secured the building on Saturday night.

All electricity and natural gas lines to the building are turned off, Culver said.

The property is owned by William T. and Suzanne O. Lafond, according to the West Springfield Assessors Office Web site.