A 69-year-old woman was found dead aboard a boat that caught fire while docked at the Port of Los Angeles at Terminal Island early Monday, fire officials said.

A 28-foot cabin cruiser was engulfed in flames when firefighters arrived at Berth 258 near the Al Larson Marina shortly after 4 a.m. They put out the fire in 16 minutes, then discovered the woman dead aboard the boat, which was still afloat, said Los Angeles Fire Department spokesman Brian Humphrey.

The woman was not immediately identified. It is not clear how she died. Witnesses in the area told fire officials that the woman lived on her boat with her dog. The dog has not been found, Humphrey said.

Los Angeles Fire Department arson investigators are working to determine what caused the fire, Humphrey said.