AUBURN, Maine — A 6-year-old boy playing with a cigarette lighter ignited a Friday morning fire that seriously damaged a Fourth Street apartment building and left 43 people homeless, according to the state fire marshal’s office.

The boy set the fire on his bed in a fourth-floor apartment and then told his mother, who was in another room, about the fire, according to a release from Stephen McCausland, spokesman for the Maine Department of Public Safety.

The fire started at about 8 a.m., CBS 13 reported. Heavy smoke was seen coming from the fourth floor. All residents escaped the building, which sustained heavy smoke, fire and water damage.

An Auburn firefighter was treated at a local hospital for a shoulder injury suffered while fighting the fire, according to CBS 13.

According to McCausland, the boy will be referred to a local juvenile firesetter prevention program.