The attack is the biggest of its kind on a US pipeline.
"At this time, our primary focus is the safe and efficient restoration of our service and our efforts to return to normal operation,” the company said in a statement.
The company has not yet mentioned when it will resume service.
US crude futures, which settled 0.29 per cent higher at $64.90 per barrel on Friday, are expected to make significant gains due to the outage.
"I expect WTI [West Texas Intermediate] to open higher tomorrow as it has the potential to disrupt supplies throughout the US North East," said Jeffrey Halley, Asia Pacific senior market analyst, at Oanda.