HOLYOKE — Early investigations into the back-to-back fires that ripped through two apartment buildings this week are concluding that the blazes were accidental in nature, fire officials said Wednesday.

The state fire marshal’s office said that Tuesday’s fire at a four-story apartment building at 733 High St., which kept firefighters on scene for 16 hours until after midnight, was likely caused by a power strip plugged into a multi-plug adapter.

Ongoing investigations also show that another fire, which started at 4 p.m. Monday at a four-story apartment building at 131 Clemente St., appears accidental, officials said.

“This investigation is still active, but we know that overloaded power strips and extension cords are a common cause of electrical fires,” State Fire Marshal Jon M. Davine said in a statement. “These devices are designed for temporary use and can’t handle the current drawn by too many appliances. Please use them sparingly, and always plug them directly into a wall outlet — not another extension cord, power strip, or adapter.”

Tuesday’s fire on High Street, near the corner of Franklin Street, displaced residents from 45 apartments but no injuries have been reported.

Holyoke Fire Chief John Kadlewicz praised the 50 firefighters who battled the blaze that broke out at 8:15 a.m., saying that they “did a tremendous job under extremely difficult conditions.”

“They faced heavy fire with zero visibility at times, with snow and ice making their work even harder,” said Kadlewicz. “This fire could have spread even further and threatened even more homes, and I want to recognize their extraordinary performance in containing it. And all of us want to thank our mutual aid partners, the Holyoke Police Department, and Holyoke Emergency Management for their strong support.”

Monday’s fire on Clemente Street displaced 26 families. So far, fire officials identified the area of origin as a second-floor apartment but have not determined the exact cause. Based on an examination of the scene and witness interviews, officials are looking at accidental factors and do not believe it was intentionally set.

Firefighters battle a large building fire at 131 Clemente Street in Holyoke Monday afternoon, December 1, 2025. CHRISTOPHER EVANS / For the Gazette

The Red Cross of Massachusetts, Salvation Army, Enlace de Familias, and other partners are supporting displaced residents. The Department of Fire Services delivered a Rehab unit to both fires to support firefighters’ health and safety on the job.

“We’re relieved that no one was injured in this week’s fires, but this has been a terribly challenging week for the community,” said Kadlewicz. “Our hearts go out to all the families who lost their homes and belongings. We ask anyone who wants to help to make donations to Enlace de Familias. This will ensure that your support goes directly to the people who need it most.”

Samuel Gelinas is the hilltown reporter with the Daily Hampshire Gazette, covering the towns of Williamsburg, Cummington, Goshen, Chesterfield, Plainfield, and Worthington, and also the City of Holyoke....