WINTHROP, Maine — An alert 12-year-old saved his two older siblings from a fire that broke out at their home Saturday morning, according to firefighters.

“He did a great job,” Winthrop fire Chief Dan Brooks said of the child on Saturday afternoon. “He did all the right things in the right spot.”

The boy woke in his bedroom around 8 a.m. to the smell of smoke and the sound of a fire alarm, Brooks said. He ran to his older brother’s room to wake him and his older sister’s room upstairs to wake her. All three siblings escaped safely with the family dog. Brooks didn’t have ages for the other two siblings, but said they were both in their teens.

“Basically, he got everyone out of the house before it got really untenable inside the building,” Brooks said.

The children’s parents had left the house, a four-unit apartment on Route 133, shortly before the fire broke out to go to the gym, according to Brooks.

By the time firefighters arrived, everyone had evacuated the building, including residents of two other apartments. The fourth apartment is vacant.

Brooks said the fire was out within 20 minutes, but crews stayed on scene for about two hours checking other parts of the building to ensure there wasn’t fire elsewhere.

The fire was contained to a small area in the kitchen, according to Brooks, but the family will need to relocate until the damage can be repaired. The American Red Cross is assisting. Residents of the other two apartments should be allowed to move back in as soon as Saturday night, Brooks said.

The cause of the fire remains under investigation, but Brooks believes it could have started near the heater or microwave in the kitchen.

Fire crews from Monmouth, Manchester and Augusta assisted in the fire response, Brooks said.

Follow Nick McCrea on Twitter @nmccrea213.