WATERVILLE —  A fast-moving fire that destroyed a three-story apartment building on Water Street Monday night has been ruled arson.

Sgt. Timothy York of the State Fire Marshal’s Office said today that the fire was intentionally set by two juveniles. York did not know whether they had been charged with arson yet.

Barbara Dow and her son, Tony, were the only tenants in the four-apartment building and got out with help from some good Samaritans, according to Beverly Busque, who lives next door.

Busque said that before the fire started, there were youths outside her house, messing around.

“I heard windows crashing — I was watching TV,” she said. “I came out of there screaming her name — Barbara! Barbara! A whole bunch of people went in and got her out of there. I swear to God, they were angels. I don’t even know who they are.”

About 40 firefighters from Waterville and Winslow battled the blaze as more than 100 people lined the street and lawns, watching.

Firefighters escorted Dow, who was visibly shaken, down the sidewalk.

The apartment building at 25 Water St. is located across Water Street from the Hathaway Creative Center, where spectators peppered the parking lot, taking photos with their cell phones. Children were running around yelling.

The owner of the building, Roger Moody, of Sidney, said he has owned it 10 or 12 years. He got a call from someone, telling him his building was on fire, and he rushed to the scene, he said.

Dow and her son, 17, lived on the second floor about 20 years, according to Busque.

Waterville fire Lt. John Gromek said Fairfield firefighters were called to cover the station. He said around 8:15 p.m. that the cause of the fire was unknown.

Waterville police Sgt. Bill Bonney said he called a police detective to the scene. Det. Lincoln Ryder was with Bonney later in the night. They said more information on the fire would likely be available today.

Scott McAdoo, 29, who lives off Water Street, said he was watching television and listening to a police scanner when he heard about the fire. He walked out the door and down the hill, he said.

“All I saw was fire. The whole front end of the building was engulfed in flames.”

Heather Merrow and her husband, Ralph, learned of the fire from their son, Nicholas, who had been fishing with a friend and saw smoke near the porch, the Merrows said.

“The sad part is, it’ll be an eyesore for a long time,” Heather Merrow, 45, said, as she looked up at the very large, burning building, surrounded by trees that also were burning.

Amy Calder — 861-9247

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