(AP) — An early morning fire has prompted the closure of a South Sioux City oat processing plant.

Firefighters responded about 3 a.m. Monday to a fire on a manufacturing line at the Viterra grain processing plant.

Tracey Shelton, a spokeswoman for plant owner Richardson International, says the plant is closed while crews assess the damage.

Shelton says none of the 10 workers at the plant when the fire broke out were injured. The plant employs 60 people.

The cause of the fire wasn’t known Monday.

The plant was built in 1989 and processes oats used in cereal and other food.