A mother and her three young children were killed in an early-morning fire in Caribou on Thursday, the state fire marshal’s office said.

Norma Skidgel, 28, was pronounced dead at the scene. Also killed were Mason and Madison Delisle, her 2-year-old twins, and 3-year-old Trenton Delisle.

After they were pulled from the fire by Caribou firefighters, the children were rushed to Cary Medical Center, where they were all pronounced dead. All four were recovered from a back bedroom in the mobile home.

Fire investigators found a smoke detector in the home, but the battery had been removed. It was not known if there were other smoke detectors in the home, or if they were working.

The four bodies will be taken to the state Medical Examiner’s Office in Augusta, where they will undergo autopsies and examination, likely on Friday.

Three other people – Amy Bouchard and her two sons – also lived in the mobile home, according to authorities. Bouchard and one of her sons were out of the house walking to a bus stop when the fire began. The home was ablaze when she returned. Her other son was staying elsewhere Wednesday night.

Bouchard, who is Skidgel’s sister, was treated for smoke inhalation after she tried to enter the mobile home.

Reached Thursday, Yvonne Skidgel, Norma Skidgel’s mother, declined to comment.

Seven investigators from the Office of the State Fire Marshal are working to determine the fire’s cause. Photos distributed by investigators show the mobile home was mostly destroyed. Charred kitchen appliances sat amid heaps of burned material.

The fire at the Westgate Mobile Home Park was reported around 7 a.m. The Westgate Mobile Home Park is located about a mile southwest of Loring Commerce Centre, on the town line with Limestone. From aerial photos, the park appears to contain about 18 mobile homes.

The owner of the mobile home park is Maggie Ventures, LLC, according to Caribou city records. The company is located in Las Vegas, Nevada. Lawrence Phillips, the company’s manager, could not be reached for comment Thursday. The property was purchased by Maggie Ventures in October 2013, according to the City of Caribou.

The fire is the deadliest in Caribou in modern times. Of the 25 people killed in Maine by fires this year, 11 deaths occurred in November, said Stephen McCausland, spokesman for the Maine Department of Public Safety.

Six young people died Nov. 1 in a blaze on Portland’s Noyes Street; investigators are still working to determine the cause. On Wednesday, an elderly St. Francis man was killed after he tried to start his wood stove with gasoline.