A blast rocked the tiny north-central Iowa town of Clarion this morning. The town’s mayor, John Ofstethun read a brief statement at city hall. He saidshortly after 7 A.M., there was an explosion in the head house on top of the Clarion Co-op Elevator, also known as the North Central Elevator. One person was hurt and transported to Des Moines. The incident is under investigation and the cause is unknown.