Investigators say they still don’t know how a fire was started that destroyed a storage-unit building in Marion.

The structure fire was reported at around 12:30 p.m. Tuesday at Marion Security Storage off U.S. 2, west of Kalispell.

According to Marion Fire Department Fire Chief Katie Mast, the contents of 30 units were a total loss, but no injuries resulted from the fire. She said the units were fully engulfed upon arrival, and the blaze took three agencies approximately nine hours to extinguish.

Multiple units contained ammunition that discharged during the fire and one contained four 100-pound propane tanks that self-ventilated, Mast said.

The cause of the fire is still under investigation, she said.

Marion Fire was aided by West Valley, Smith Valley and South Kalispell fire departments.