Two explosions tore through a three-family home, igniting a fire that sent the house collapsing onto itself. Seventeen people were injured.

One person was in "extremely critical" condition, said Richard Serino of Boston Emergency Medical Services. The other people's injuries weren't considered life-threatening, he said.The three-story house collapsed after two suspected natural gas explosions ripped through it Wednesday morning, jolting other homes in the Dorchester neighborhood and sending glass shards flying.