Investigations are continuing into the cause of the explosion at the San Diego Bayfront Hilton on May 19^th. Fire officials believe the blast was the result of flames from a water heater or an electrical spark igniting natural gas that was leaking into the mechanical room. It has been determined that the blast was an accident. The investigation has been turned over to Cal-OSHA and they will decide if any of the workers violated Health & Safety codes. The explosion caused at least $5 million in damage and injured 13 workers and one firefighter. Three victims are still in medically-induced comas at UCSD Medical Center, and another remains at Scripps Mercy with orthopedic injuries.