The Public Utility Commission says that's been the case since Monday, a day after a sinkhole exposed a portion of the pipeline in West Whiteland.
Until Thursday, officials had confirmed only that a segment of the line had been closed.
Sunoco and its parent company, Energy Transfer Partners, won't be able to resume pipeline operations on the liquid natural gas pipeline until state investigators approve.
The PUC says work continues to stabilize the sinkhole. They've called in safety engineers and geophysical consultants to look at the site and develop a remediation plan.
The agency notes its investigators have the authority to bring enforcement action and to seek emergency orders to ensure public safety.
Last month, the Chester County District Attorney opened a criminal investigation into the Mariner East project.