Video: Grandfather Mourns Loss Of Grandchildren

The woman was flown to Harborview Medical Center in Seattle with severe burns, said Grays Harbor Sheriff Mike Whelan. She was first listed in critical condition, but was later upgraded to serious condition, KIRO 7 Eyewitness News reported.

The Grays Harbor County coroner identified the children as 21-month-old Alex Jardine and 17-month-old Elizabeth C. Jardine.

The boy was the son of the woman in the trailer and the girl was the woman's niece, the sheriff's department said.

Deputies with the Grays Harbor Sheriff's Department were on the scene Thursday morning, trying to figure out the cause of the fire, the sheriff said.

The undersheriff said it would take several more hours to determine the cause of the fire, KIRO 7 Eyewitness News reporter Jeff DuBois said.

All indications are that the fire was accidental.