By Karl Plume

CHICAGO (Reuters) -Several employees were hospitalized after an explosion and fire late on Sunday at a massive Archer-Daniels-Midland (ADM) facility in Decatur, Illinois, that severely damaged crop processing operations, the company and the local fire department said.

Eight workers were injured at the ADM East processing plant and six were taken to hospital via ambulance, the Decatur Fire Department said in a statement on Monday. Five remained hospitalized on Monday morning, ADM said.

The company said it was evaluating the extent of the damage and investigating the cause of the incident.

Several structures were severely damaged in the blast, including a 10-story building and adjacent buildings, the fire department said.

A plant that crushes soybeans into soybean oil and white flake for soy protein production was down on Monday, ADM said. An adjacent corn processing plant was also "temporarily down until we can safely resume operations," the company said.

A prolonged outage at the massive processing facility in the heart of the U.S. Corn Belt would put downward pressure on crop prices just as Midwest farmers are preparing to harvest their corn and soybeans. U.S. crop prices, especially for corn, have declined as export demand has slumped.

The Decatur site, ADM's North American headquarters and its largest facility globally, houses soybean crushing facilities and one of the largest corn wet mills in the world.

It has the capacity to produce 375 million gallons (1.42 billion liters) of ethanol biofuel annually, making it the largest in the country, according to the Renewable Fuels Association.

"Coming into harvest, if it is down for a week or more, that would really cripple the cash basis," said Mike Zuzolo, president of Global Commodity Analytics.

Spot basis bids for corn at ADM's Decatur location tumbled by 35 cents a bushel from late bids on Friday while soybean bids were flat. Bids have been dropping across the Midwest in recent weeks as buyers await newly harvested grain.

(Reporting by Karl Plume and Julie Ingwersen in Chicago, Evelyn Nikhila S and Baranjot Kaur in Bengaluru; Editing by Gerry Doyle, David Holmes, Susan Fenton and Sandra Maler)