Officials are investigating the cause of a house fire that killed a mother and her two young children Sunday evening.

The Island County Sheriff’s Office confirmed today the victims of a DeGraff Road house fire are a 25-year-old woman and her 3- and 5-year-old children.

The woman’s husband was not at home at the time of the fire, according to the sheriff’s office, but arrived while fire crews were extinguishing the blaze.

The sheriff’s department said the man is cooperating with investigators.

The fire, located in the 4000 block of DeGraff Road, was first reported at 4:36 p.m. Sunday, Dec. 18, according to the sheriff’s office.

Firefighters with North Whidbey Fire and Rescue and the Oak Harbor Fire Department fought the blaze.

Detectives from the sheriff’s office and Washington State Patrol Crime Lab are currently processing the scene to determine the cause and origin of the fire.

“At this time we are still in the early stages of the investigation, more information will be released when it becomes available,” the sheriff’s office said.