Residents of Charlestown building treated for smoke inhalation after two-alarm fire

UPDATE: Three charged with arson.

A fire that erupted shortly before 1 a.m. at 74 Medford St. went to two alarms, the Boston Fire Department reports.

Several residents were treated on scene for smoke inhalation; an MBTA bus was brought in for residents until the Boston Housing Authority and the Red Cross could find places for them to say. The three-story brick building has nine apartments.

Fire officials say the fire was confined to a first-floor apartment but that smoke reached throughout the building. The cause of the blaze, which did an estimated $100,000 in damage, is still under investigation.