The fire that killed an 85-year-old woman in Oxford, injured another woman and displaced dozens of elderly residents Saturday was accidentally caused by a faulty electrical connection inside a wall outlet, the state Fire Marshal’s Office said.

Fire investigators worked with a state electrical inspector to determine that a wire connected to an outlet in a first-floor common area caused the spark that ignited the blaze. The fire spread quickly to a lamp that was connected to the outlet. The flames accelerated when they reached a wicker basket full of newspapers, the fire marshal’s office said Monday.

Meanwhile, 15 displaced tenants were to spend Monday night at the Inn Town Motel in Norway, up from 10 residents Saturday night, said Ann Marie Westberry, manager at the hotel. She said the owners of the apartment complex, Speedway Inc. Madison Avenue Associates, have agreed to pay the hotel bill.

“For the most part of it, they’ll be here until the building is ready to move back in,” she said. “The Red Cross has done a tremendous job.”

Westberry said a few residents whose apartments were not close to the most damaged areas of the building were allowed to return to their units to retrieve some belongings Monday afternoon, but for those who lived near the common area where the fire began, there has been no access so far.

Killed in the blaze was Theresa Heino, 85.

Another woman, Virginia Brown, 65, who suffered smoke inhalation, was transported to Stephens Memorial Hospital in Norway in critical condition. On Monday, she was in stable condition, a hospital spokeswoman said.

Brown declined to be interviewed, and her family requested privacy as she recovers.

The complex, Oxford Meadow Apartments at 1633 Main St., which is also Route 26, houses about 40 older residents. Many are low-income tenants, have disabilities or use wheelchairs.

Extensive rescue operations were required to evacuate the other people in the building, authorities said. Rescuers had to rouse some residents from their beds and carried others out of their apartments via ladders from the ground, from aerial ladders and through windows.

Oxford Fire Chief Wayne Jones said about half of the units, on the right half of the building, were more damaged than the other side. The building’s owners have indicated plans to rebuild and reoccupy, but how long that will take is unknown, he said.

“We’re just starting down the road to trying to get that building reoccupied,” Jones said.

A spokesman for the American Red Cross of Maine said the relief organization had made contact with at least one person from each of the complex’s 38 units, and was providing various levels of support, including refilling prescriptions lost in the fire, helping residents obtain new clothes, and helping them find shelter.

The complex is owned by Robert P. Bahre, former owner of the Oxford Plains Speedway and the New Hampshire Motor Speedway and a major investor in the Oxford Casino, which was sold to Churchill Downs for $160 million in 2013. The casino and speedway are a short drive away on Route 26.

The company operates more than a dozen apartment complexes for elderly and disabled people around the state. Red Cross officials said that although the apartments are for the elderly, it’s not an assisted living facility with around-the-clock care for residents.

The building was last inspected in March 2009, according to town tax records. It was built in 1984, and is listed in “average” condition. It did not have a sprinkler system, but the facility was equipped with fire alarms, which worked properly during the fire.

When all residents will be allowed back into their units has not been determined, said Westberry, the hotel manager.

“Right now, it’s day by day,” she said.