RUMFORD – A late afternoon fire in a second-floor apartment last Tuesday was arson.

Lt. Keith Bickford of the Rumford Fire Department said on Monday that the department’s investigation as well as that of the State Fire Marshal’s Office determined that a blaze at 278 Spruce St., in one of the eight-unit apartment buildings known as Swainbrook Apartments, was intentionally set.

He said the determination was made because there was nothing on the porch that could have started a blaze.

“There was no hibachi, no grills, no candles,” he said.

Rita Arsenault, 84, the tenant of the second-floor, back apartment, was taken to Rumford Hospital late Tuesday afternoon for observation. She was treated and released.

Her apartment experienced some smoke but no damage.

Bickford said a portion of the porch and back wall was damaged before the fire was put out. He, along with fire Chief John Woulfe, estimated damage at about $3,000. Arsenault, as well as all tenants who were evacuated from the apartment house, were able to return to their homes that night.

The building is owned by Spring Street Associated, Liberty Management, Portland.

Bickford said a representative from the State Fire Marshal’s Office is due back this week to continue investigating the incident.

He doesn’t believe last week’s arson fire is related to any of the other intentionally set fires that have occurred in Rumford in recent months. Among those was a garage fire on Waldo Street on Aug. 4 that resulted in about $30,000 damage and two incidents of Molotov cocktails hurled at Hosmer Field and Hancock Street. No suspects in either incident have been arrested.

Other suspicious fires occurring during the past few months have taken place in Canton, Mexico and Dixfield.