The cause of an explosion that critically injured three people and destroyed one home on Bayard Street in Baltimore’s Pigtown neighborhood remains under investigation. The victims are a 16-year-old girl, a 48-year-old woman and a 70-year-old man. Two of the victims were inside the house that exploded and the third victim was a man who tried to rescue them when it collapsed. Fire officials say another home might have received structural damage. Baltimore Gas and Electric shut off service to the entire block while first responders were on the scene. The utility company says it completed upgrades to the line that serves the neighborhood last month.