MASON CITY (AP) - Soy Energy officials believe an explosion at the company's biodiesel plant in Mason City originated in a tank inside a restricted area.
No one was injured in the blast Tuesday evening.
Jeff Oestmann, CEO and general manager of Soy Energy, said the investigation is ongoing, but authorities are focusing on the tank, which had only minimal damage.
Soy Energy, which employs 40 people, produces biodiesel from soybeans and corn stillage.