Authorities say an explosion and fatal fire in northwest Iowa near LeMars was likely caused by a cigarette, not an illegal drug lab. The Plymouth County Sheriff says the dead man is 20-year-old Ron Bigley who lived just west of LeMars. The state fire marshal says it was not a meth lab, but a propane tank was being used and a cigarette probably caused the tank to ignite in the garage about 2 A.M. Thursday. Damage was extensive. Bigley was identified through dental records.