Saturday afternoon's fire was deliberately set, officials say.
The cause of the fire has been determined to be arson after an investigation by the Fire Department, State Fire Marshal's office, Fort Dodge Police and Iowa Division of Criminal Investigation, said Fire Chief Kent Hulett.
The investigation is ongoing.
Crews were on the scene earlier than 9 a.m. Sunday to investigate the fire that destroyed a former church Saturday afternoon.
"We are bringing assets on the scene for a thorough on-scene investigation," said Fire Chief Kent Hulett said. "It can be time consuming."
Hulett said he could not say what caused the fire, or whether it is considered suspicious, but anticipated that more information will be available this afternoon.
Officials from the State Fire Marshal's office were there, and brought in an accelerant-detecting dog to help with the investigation.
The building is located at the corner of First Avenue North and Eleventh Street, next to the Beacon of Hope Men's Shelter. The first fire call came in at 2 p.m. Saturday, and six other fire departments assisted until the blaze was sufficiently contained at 5:20 p.m.