DES MOINES, Iowa (AP) — Investigators have determined that kitchen rags self-ignited to start a fire that engulfed the Plaza Lanes bowling alley in Des Moines. The Des Moines Fire Department said in a news release Friday that more than two dozen people from various agencies were involved in the investigation, which concluded the Dec. 18 fire was accidental.

Fire experts say spontaneous combustion can occur when heat generated through rapid oxidation causes various materials to catch fire. A Consumer Product Safety Commission study found that oil residue as low as 3 percent in fabrics can lead to ignition.

Plans for a new alley complex include a larger arcade, laser tag and a sports restaurant and bar.