PORTLAND, Ore. -- A house fire in rural Oregon that killed four children and critically burned three other family members started with a portable space heater that was being used after a fireplace malfunctioned, a volunteer fire chief said Thursday.

Combustible materials placed too close to the heater ignited and started the blaze in the tiny timber town of Riddle, Fire Protection District Chief Rich Holloway said in a post on the district’s Facebook page.

Holloway did not immediately return two calls but City Manager Kathy Wilson confirmed the authenticity of the Facebook post in a phone interview.

The fire killed four children ranging from 4 to 13 and devastated the tiny town with a population of fewer than 1,000 people. Riddle is about 200 miles south of Portland.

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A component of the fireplace that forces heated air back into the home malfunctioned several days before the blaze early Wednesday and the family was using the heater until they could get it repaired, Holloway wrote.

“All the burn pattern indicators, witness statements and the statement from the father on first arrival, all collaborate,” he said.

Some members of the all-volunteer fire department knew the family, Wilson said.

“In a small town like this, everyone knows each other and this has been devastating,” she said. “It is just such a tragedy. It’s something we’ve never seen before. It has affected everyone.”

Community members held a candlelight vigil at a church late Wednesday that attracted more than 300 people.

Grief counselors were on hand at schools in the South Umpqua School District, where some of the children attended class, said Superintendent Tim Porter.

The district has just 1,450 students in all grades, he said.

The three survivors were transported to Portland for treatment of critical burns.

James Keith Howell, 39, Tabitha Annette Howell, 38, and Andrew Hall-Young, 13, were in critical condition in the burn center, Julie Reed, a spokeswoman for Legacy Emanuel Medical Center in Portland, confirmed on Thursday.

In a statement released through Legacy Emanuel, family members huddled at the survivors’ bedsides declined interview requests.

“The community has been so generous in their response to our needs with prayer and offers of support, and we are very grateful,” the statement read.

“At this time, we are requesting continued prayers and your respect for our privacy, as we are grieving our loss.”

Killed were 4-year-old Gwendolyn Howell, 7-year-old Haley Maher, 10-year-old Isaiah Young and 13-year-old Nicholas Lowe.

Nicholas Lowe was a foster child, said Douglas County Deputy Dwes Hutson.

Tabitha Howell is the mother of the remaining children and is married to James Howell.

Howell is the father of the youngest victim and the stepfather of the two victims, ages 7 and 10, and the surviving 13-year-old.