STUTTGART, Ark. —  An explosion rocked a Riceland Foods plant in Stuttgart on Tuesday, killing one person.

Two workers were repairing an empty tank used to process soybean oil when the explosion occurred about 8:30 a.m., according to company spokesman Bill Reed. One of the workers was killed, Reed said. His name was not released, pending notification of his family.

No one else was injured, Reed said.

Officials were investigating the cause of the explosion.

"At this time we're not really sure what exploded. It's still being investigated," Stuttgart Fire Department Capt. Kie Sherman said.

The workers were doing routine maintenance atop the Riceland Foods Soy Division storage building. Emergency workers used a crane to reach the fatally injured man and lower him to the ground. Sherman said the building wasn't on fire when firefighters arrived.

Riceland is a major soybean processor and rice exporter. A cooperative, the company also provides marketing services for rice products, soybeans, and wheat.