Four young adults who were found dead Friday night in a cabin in Byron, apparently from carbon monoxide poisoning, were discovered when the father of two of them arrived to celebrate his daughter’s birthday, officials said Saturday.

Oxford County Sheriff Wayne J. Gallant identified the victims as Brooke Wakelin, 21, and her boyfriend, Keith Norris, 23, both of Attleboro, Massachusetts; and Wakelin’s brother, Matthew Wakelin, 18, and his friend Deanna Lee Powers, 22, both of Mansfield, Massachusetts.

The four had come up from Massachusetts to the Wakelin family’s cabin Tuesday evening, Gallant told the Maine Sunday Telegram, and apparently hooked up a generator to run a refrigerator in the cabin, which did not have electricity.

The generator was in the basement, Gallant said, and there was no exhaust from the device to the outside of the cabin.

The generator was still in the on position, but it had run out of gasoline when authorities arrived Friday night, the sheriff said.

Brooke Wakelin would have turned 22 on Saturday, Gallant said, and the group planned to celebrate the occasion along with Matthew Wakelin’s recent graduation from high school.

Gallant said the cabin on Bateman’s Lane is one of dozens in the area along the Swift River, which is popular for its swimming holes. The cabin was relatively secluded from others in that part of Byron, he said.

Mark Wakelin of Braintree, Massachusetts, knew his children were going to the cabin and planned to join them Friday night, Gallant said. When he arrived, Wakelin discovered the bodies of his daughter and her boyfriend on the first floor of the cabin and ran to a nearby home with a landline phone to call police around 8:30 p.m., Gallant said. There is spotty cellphone coverage in the rural area, he said.

Police and rescue personnel found Matthew Wakelin and Powers upstairs, Gallant said.

The sheriff’s office is waiting for the state medical examiner to determine the cause of the deaths, Gallant said, but the working assumption is that the four died from carbon monoxide poisoning, most likely on Tuesday night.

“More than likely it happened the first night there,” he told The Associated Press. “It’s a shocking and terrible reminder to people that carbon monoxide is dangerous. You never have a generator in the house.”

Judy Boucher, owner of Coos Canyon Cabins and Campground, about 2 miles from the Wakelins’ cabin, said the family had owned the cabin for some time.

Byron is a town of 145 people just north of Rumford in western Oxford County.

Staff Writer Beth Quimby contributed to this report.