NORTHBOROUGH — The cause of last week’s fatal fire in Northborough will be officially undetermined, but there is no evidence that the fire was intentionally set, officials said today.

Northborough Fire Chief David L. Parenti, State Fire Marshal Peter J. Ostroskey, and Worcester County District Attorney Joseph D. Early said Friday’s fire on Maple Street originated in the bedroom of Unit 1, where 40-year-old Kevin Hunt perished. The relevant National Fire Protection Association standard requires investigators to classify a fire as undetermined if they cannot eliminate all but one possible cause of a fire: while a single cause could not be determined to the exclusion of all others, the improper disposal of smoking materials or an unspecified electrical event are considered possible causes.

“On behalf of the Northborough Fire Department, I’d like to express our deepest condolences to Mr. Hunt’s loved ones,” said Chief Parenti.

An examination of the scene after the fire found no working smoke alarms in any of the five residential units, one of which was vacant.

“Smoke alarms can’t help you escape a fire if the batteries are missing or expired,” Chief Parenti said. “If the alarm is beeping or chirping, don’t just remove the batteries. It’s a sign that the batteries or the device itself needs to be replaced. The State Fire Code requires replacement smoke alarms in older one- and two-family homes to be photoelectric and have 10-year, sealed, non-replaceable, non-rechargeable batteries and a hush feature. This is to make it easier for people to maintain these important safety tools.”

“In the average house fire, there are only one to three minutes to escape after the smoke alarm sounds, so it’s critical to keep them working and test them monthly,” said State Fire Marshal Ostroskey. “Smoke alarms should be replaced 10 years after the manufacturing date printed on the back. Carbon monoxide alarms usually need to be replaced after five to seven years. If the alarm has replaceable batteries, the batteries should be changed twice a year, usually at the beginning and end of Daylight Saving Time.”

The Northborough Fire Department responded to 129 Maple St. at about 4:20 am on Sept. 10 to find significant smoke and flame showing at the two-story, five-unit residence. Firefighters made entry while fighting the fire and found the occupant of Unit 1 deceased inside; all other occupants escaped safely. Mutual aid companies from Westborough and Southborough provided assistance at the scene, and one Southborough firefighter was transported to an area hospital for heat exhaustion. Damage from the fire left the building uninhabitable.

The origin and cause of the fire were jointly investigated by the Northborough Fire Department, the State Police Fire & Explosion Investigation Unit assigned to the State Fire Marshal’s office, and State Police detectives assigned to the Worcester County District Attorney’s office. The Department of Fire Services’ Code Compliance Unit provided assistance.

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