A six-alarm fire caused extensive damage to a Cambridge apartment building, but authorities say all the residents escaped unharmed.
The fire on Massachusetts Avenue was reported just after midnight Thursday.
Fire Chief Gerald Reardon says it appears as if the blaze started in the basement of the six-floor building but quickly moved floor to floor up a utility shaft, making it difficult to battle.
The older 57-unit building did not have a sprinkler system.
Reardon says 125 firefighters responded, and some suffered minor injuries.
The cause remains under investigation.