ANCHORAGE - The state has asked federal regulators to step in and help investigate the rupture of a natural gas pipeline at Prudhoe Bay.
The Sept. 29 rupture broke apart the steel pipe and flung a piece of metal across the tundra in the nation's largest oil field. No one was hurt.
The state Petroleum Systems Integrity Office has begun an investigation.
The agency has asked a federal agency, the Pipeline and Hazardous Materials Safety Administration, to assist.