An overloaded electrical cord and power strip are believed to be the accidental cause of a blaze that destroyed a single family home in Oak Bluffs Tuesday morning and claimed the life of a dog, Oak Bluffs deputy fire chief Tony Ferreira said Thursday.

Volunteer firefighters were called to the scene at 9 Kim’s Way off Wing Road just after 10 a.m. Tuesday; when they arrived the one-story house was fully involved. Fire departments from Tisbury and Edgartown responded to a call for mutual aid. Wing Road was closed to traffic. The Oak Bluffs ladder truck was on the scene in the densely-built neighborhood. Firemen went up onto the roof of the house and cut an opening to vent the fire. Heavy smoke poured from the building, limiting visibility.

Thick smoke made air packs necessary for volunteer firefighters. — Mark Alan Lovewell

Assistant fire chief John Rose, who is also chief of emergency services for the town, said when firefighters arrived there was ammunition exploding inside the house. “That made it a particularly dangerous fire for us,” he said. “We had to go into defensive mode. There was an array of all sorts of caliber ammunition.” He said the tenant who had the ammunition was a gun collector and had all the necessary legal permits to possess firearms and ammunition.

The home was unoccupied by humans at the time of the fire but there was a Labrador retriever inside that did not survive. The home had been rented out to a couple, Greg and Heather Arpin, Mr. Ferreira said. The home is owned by Craig MacCormack.

The fire was contained by just before noon, but the house was a total loss, Mr. Rose said. An adjacent guest house on the property was not affected.

Home was entirely blackened by flames and windows shattered. — Mark Alan Lovewell

Working with the state fire marshal’s office Tuesday afternoon, investigators determined that the likely cause was an overloaded power cord found in the rear of the building.

Mr. Rose said the overloaded power cord and power strip in the back of the house that caught fire were connected to an outdoor RV. Mr. Ferreira said the homeowner had spent the night before the fire in the RV.

Mr. Rose praised the response from some 35 volunteer firefighters from the three down-Island towns. “We were shorthanded at the initial phase of the fire. It is vacation week. It was great to have two surrounding communities step in to help and offer their help,” he said.

This story has been changed since the original version, which reported inaccurately that John Rose was deputy fire chief. Mr. Rose is assistant chief.