WARREN, Ohio - State investigators want to know how an estimated 100 gallons of oil made it's way into the Mahoning River in Warren.

The oil skim on the river was discovered late Monday afternoon behind the Packard Museum on Mahoning Avenue. Warren fire department and hazmat deployed containment and absorption booms to keep the oil from drifting downstream.

Pollution control workers used a vacuum truck to retrieve the remaining oil Tuesday afternoon. The Ohio EPA says the oil entered the river through a large 84 inch storm sewer behind the Packard Museum. 

The source of the oil was tracked to an industrial area around Griswold Street NE and Bronze Road NE. But exactly where the oil came from had not been determined.