(Griswold, Iowa) – [UPDATED] Five people were overcome by the effects of natural gas this morning, in Griswold. A construction crew hit a gas line near the Griswold Care Center at around 8:45-a.m., prompting a call to MidAmerican Energy to shut the line off.  Cass County Emergency Management Coordinator Mike Kennon told KJAN News, the patients affected were treated at the scene for light-headedness and nausea. None of the patients required transport to the hospital.