CHICAGO, Illinois (CNN) -- Thousands of gallons of oil sludge are being cleaned up along a 3-mile section of the Des Plaines River early Monday, following a spill a day earlier that had forced a temporary closure of the river.
About 4,500 to 6,000 gallons of sludge leaked into the river Sunday, the result of a 65,000-gallon spill from a holding tank at a Caterpillar facility in Joliet. Most of the sludge from the heavy-equipment manufacturer ended up on land.
The thousands of gallons that leaked into the river killed an unspecified number of wildlife -- "nothing bigger than your hand," mostly fish and frogs, U.S. Coast Guard spokesman William Mitchell said early Monday.
The river reopened to traffic Sunday evening, though watercraft were limited to passing through the area in single file.
The Coast Guard and the Environmental Protection Agency were coordinating efforts to contain the spill, including the use of a containment boom and vacuum trucks.
In a written statement, Caterpillar acknowledged the spill but did not offer specifics.
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