AMHERST, SOUTH DAKOTA — The Keystone Pipeline leaked 210,000 gallons, or 5,000 barrels, of oil Thursday in Marshall County, South Dakota near Amherst.

Officials are currently investigating the cause of the leak, CNN reported.
TransCanada, the company that owns the pipeline, said it detected a drop in pressure around 6 a.m. on Thursday morning and shut down the pipeline.
The pipeline runs from Hardesty, Alberta to Cushing, Oklahoma and Wood River/Pakota, Illinois.

The company said in a statement, "the section of pipe along a right-of-way approximately 35 miles (56 km) south of the Ludden pump station in Marshall County, South Dakota was
completely isolated within 15 minutes and emergency procedures were activated."

TransCanada said it received permission from the landowner to investigate the spill and plan cleanup, the Washington Post reported.

This would be the largest Keystone oil spill to date in South Dakota, said state spokesman for the Department of Environment and Natural Resources Brian Walsh, CNN reported.