CHICAGO, June 25 (Xinhua) -- A U.S. railway company and Iowa State are continuing their joint efforts on Monday to contain the oil spill following a tanker train derailment.

Fourteen cars of the derailed train have leaked some 230,000 gallons (about 870,000 liters) of crude oil into the flooded fields in Lyon County, northwestern Iowa since Friday, according to Burlington Northern Sante Fe (BNSF) officials.

The train company has built a temporary road to the site along a flooded stretch of tracks, reported Iowa Radio, adding clean-up operations have been underway around the clock.

BNSF spokesman Andy Williams said that at least ten of the 32 derailed cars have already been drained of oil, with another seven being moved to nearby field to be disassembled. Skimmers and booms have been placed near the derailment site to capture the spilled oil.

Williams said the whole clean-up process will possibly take several weeks, if not months.

The cause of the derailment is unknown but both the train company and local officials believe that flooding was a major factor leading to the accident early Friday.