Investigators are trying to figure out what caused a house fire in the city's south side Sunday.

Crews say the fire began on the back deck of a home at 2024 57 Street before making its way up the wall and into the home.

"We don't know what caused it yet," said Mike Prangley, fire investigator with the city.

"I need to talk to the homeowners to find out what was on the deck that could have caused it."

Investigators say the fire caused structural damage. 

They haven't been able to contact the homeowners.

No one was in the home at the time of the incident.