Fire Thursday afternoon heavily damaged a house at 12540 Highway O in Ralls County.  The house dates back to the 1830s. The alarm was turned in around 4 p.m.

Hannibal Rural Fire Chief Mike Dobson says one person lived in the house but no one was home when the fire started. The homeowner's father lives in a trailer behind the house and reports hearing a loud pop. When he looked at the house, flames were coming out of the back door.

Fire officials haven't determined a cause.