A man and three children were killed early Monday in a house fire in east-central Kansas, authorities said.

Franklin County Sheriff Jeffry Curry said the fire was reported about 1:40 a.m. Monday, and the interior of the home was engulfed in flames when firefighters arrived at the home, he said.

The victims were identified as Bryce S. Schendel, 25; Zoey S. Schendel, 5 months old; Jace D. Best, 6; and Ayden L. Best, 5.

A preliminary investigation by the Kansas State Fire Marshal’s office and the Kansas Bureau of Investigation found that the fire appeared to be accidental and was likely caused by an electrical circuit and extension cord that was attached to a space heater inside the home.

Two members of the family survived the fire and were identified as Ashley L. Schendel, 24, and Alexis K. Best, 9, Curry said. He did not provide details on the family’s relationship.

He said Ashley Schendel and Alexis Best were outside the home when firefighters arrived and were being treated at Kansas City area hospitals for smoke inhalation and were in stable condition.

Curry said Bryce Schendel and the three children who died were found in different areas of the house.

Richmond is a town of around 490 residents located about 60 miles west of Kansas City.