A firefighter was injured while assisting with a house fire on River Street in West Newton Monday morning.

A second floor resident of the multi-family home, who spoke with WHDH, discovered the fire around 9:30 a.m. and called 911.

One firefighter was injured, but no details on that firefighter’s identity or health condition are available.

Fire Chief Greg Gentile told Boston 25 News that the Boston Marathon, with the crowding and roadway closures it brings, created an obstacle to getting fire trucks to the fire, and mutual aid was brought in from Boston, Waltham and Watertown.

A cause of the fire has not been announced.