NEW CARLISLE, Ind. (AP): Investigators say a northern Indiana business where a firefighter was killed in a roof collapse was too badly damaged for them to determine what caused the blaze.

The state fire marshal's office said Thursday that the Aug. 6 fire at K-Fex Inc. in New Carlisle has been ruled as undetermined and that accidental causes couldn't be ruled out.

Firefighters were working to set up a hose inside the trucking business when the roof collapse killed 41-year-old New Carlisle assistant fire chief Jamie Middlebrook. Another firefighter suffered a broken leg.

State Fire Marshal Jim Greeson says foul play isn't suspected in the blaze about 15 miles west of South Bend, but investigators couldn't find enough evidence to list the fire as accidental.