JANESVILLE, WI (Ben Caxton) — Two people are hurt after a duplex explosion rocked a neighborhood in Janesville late Monday night. `A fire investigator says the explosion was likely triggered by someone who lit a cigarette near a natural gas leak. One of the people inside reported smelling gas before the other person lit that cigarette. One side of the duplex was fully on fire when help arrived. The two people living there were taken to the hospital — one of them with serious injuries. The person living in the other half of the duplex was not hurt.