Drone footage captured in Marengo, Iowa, shows crews responding to a fire after an explosion at a plant Thursday.The Iowa State Patrol tells KCCI that the explosion happened around 11:20 a.m. on Thursday. Many agencies responded within a 30-50 mile radius. The state patrol tells KCCI that preliminary findings indicate that approximately 30 people were in the plant. All of those people have been accounted for. State patrol says there are no confirmed deaths.The fire is still burning and crews are using foam and water to put it out. The state Fire Marshal is on site trying to find a cause.Watch: Sky 8 drone footage of Marengo fireWatch: Explosion and fire in MarengoWatch: Video shows heavy smoke, flames at site of Iowa explosion, fire