WATERVILLE — Fire and police officials are investigating a fire inside the former Boys & Girls Club at 6 Main Place that is suspicious in nature, Waterville fire Chief Shawn Esler said Wednesday.

The fire was reported about 3:30 p.m. Tuesday at the large, vacant building located between Main Street and College Avenue, about a quarter-mile from the fire station. Esler said a piece of plywood attached to the outside of the building had a small hole in it and smoke was coming out of the hole.

“When the units arrived they removed that piece of plywood and learned that smoke had filled the building, so they immediately put out a second alarm for mutual aid,” Esler said.

He said the fire turned out to be “relatively small” so the call for mutual aid was canceled. Fifteen firefighters, as well as Delta Ambulance, responded to the scene and firefighters left shortly before 7 p.m.

“The fire appeared suspicious in nature,” he said, adding that the Office of State Fire Marshal and city police were notified to assist in the investigation.

Police Chief Joseph Massey said Wednesday that the fire apparently was started with some debris in the pool area. He said it appeared someone may have tried to warm themselves with the flames. There were food wrappers nearby but no sleeping bags or other evidence to suggest anyone was living in the building, though it appeared people have been going in and out of it, Massey said.

“So the fire marshal was called in and one of our officers is assisting the fire marshal,” Massey said, “and they are trying to locate a person of interest.”

The building was owned by Uria Pelletier, a contractor and former city Planning Board member who said Wednesday that he sold the building last year to an investment group.

Pelletier said he has warned a member of the group to secure the building because it is an attraction for kids. The roof over the old pool area — not a newer pool inside — is caved in, so water gets into the building, according to Pelletier.

“If a kid fell in that pool, they’d drown,” he said. “It’s extremely dangerous and that’s why the building needs to be secured.”