WATERVILLE — The state fire marshal’s office is investigating a Wednesday night garage fire at 5 Belmont Ave. that destroyed the garage and damaged multiple vehicles.

No one was injured in the 9 p.m. fire, which was fought by about 30 firefighters, according to a news release from the Waterville fire department Thursday morning.

The release said the cause of the fire is still under investigation, that Capt. John Gromek of the Waterville Fire Department is the primary investigator and an investigator from the Office of the Maine State Fire Marshal will assist.

Damage included the loss of the detached garage, a 2006 Dodge pickup truck and a boat. An antique half-ton military vehicle was damaged, and the fire melted vinyl siding on the house, which is about 15 feet from the detached garage.

All the occupants of the two-apartment building, owned by Robert Butcher, were safely evacuated, according to the release.

Deanna Butcher, who lives with her husband in the downstairs apartment, said Wednesday night that she believed the blaze’s origin was suspicious, but doesn’t know who would have set it.

Upstairs tenant Rick Mahew discovered the fire when he smelled burning plastic and looked out the window to see the garage in flames.

Butcher, 55, said once they saw the fire, it was already well underway. “As soon as we came outside we saw the boat, the truck, the garage — all of it — engulfed,” she said.

Others who saw the fire Wednesday night said it was preceded by a loud boom.

Belmont Avenue is off Western Avenue, near the Elm Street end. Traffic on Belmont and Western avenues was blocked off as the fire was fought.