A fire inspector was at a loss Friday to say what started a blaze at 630 S. 14th St. on Thursday evening.

The fire consumed nearly everything, and the department lists the origin as undetermined, said Jason Ziph, an inspector with the St. Joseph Fire Department. The values of the house and contents are estimated at $40,000 and $20,000 respectively, he said.

Three people were living in the home and weren’t injured, Mr. Ziph said.

The Midland Empire Chapter of the American Red Cross provided assistance Thursday night and met with the people again on Friday, said Karla Long, emergency services director for the local chapter.

An ambulance transported Jamey McVicker, the driver on the Rescue 9 firetruck, to Heartland Regional Medical Center. Mr. McVicker was treated for heat exhaustion and dehydration, and five other firefighters received oxygen treatments at the scene, said interim fire Chief John Nelson.

“It was a very dangerous situation for them,” Mr. Nelson said.

Mr. McVicker was fighting the fire upstairs when the first floor reached about 1,100 degrees, Mr. Ziph said. The resulting explosion blew Mr. McVicker through a door and knocked his helmet off, he said. Later the second floor also exploded, he said.

The older, two-story wooden house used a balloon frame construction method, which doesn’t put any fire stops in the walls of the house. That type of construction contributed to the speed of the fire spreading, Mr. Ziph said.

Firefighters remained on the scene until 1 a.m. Friday.

Marshall White can be reached at marshall@npgco.com.