BREAKING: Keystone oil pipeline ruptures

The Keystone oil pipeline was shut down Tuesday morning after it ruptured in North Dakota, with the spill confined to an agricultural field.

The cause of the rupture and the volume of crude oil spilled were not immediately clear. An employee working at the site near Fort Ransom heard a “mechanical bang” and shut down the pipeline within about two minutes, said Bill Suess, spill investigation program manager with the North Dakota Department of Environmental Quality.