The operator of the Keystone oil pipeline brought the conduit back into service, putting an end to a week-long outage caused by an estimated 3,500-barrel spill in rural North Dakota.

An employee on a pump station heard what was described as a mechanical bang early Tuesday morning, an official told CBS News.

The nearly 2,700-mile Keystone oil pipeline was shut down Tuesday morning after it ruptured in North Dakota, halting the flow of millions of gallons of crude oil.