An infant was critically injured in a fire near Oakville early Monday morning and his father suffered burns when he went inside the burning structure to rescue his son, the Grays Harbor Sheriff’s Office said.

The fire was in a 20-foot-by-30-foot shed where the child and his parents were staying, said Undersheriff Brad Johansson. The Sheriff’s Office was called about 1:23 a.m. to the fire on Gibson Creek Road and firefighters were there.

According to the Sheriff’s Office release, the 8-month-old infant was sleeping in the shed when the fire was discovered and the parents were in the main residence next to the shed when the fire started.

The infant suffered burns and smoke inhalation and was air lifted to Harborview Medical Center in critical condition. The 44-year-old father sustained less serious burns and was taken to a hospital where he was treated and released, according to the Sheriff’s Office.

Sheriff’s Office fire investigators are trying to determine the cause and origin of the fire. Investigators said they had seen nothing suspicious about the fire at this point in their investigation, said Johansson, who expressed sympathy on behalf of his office.