The Coast Guard said the drilling rig broke loose from a Shell-contracted ship, the tow vessel Aiviq, Monday afternoon, the Anchorage Daily News reported Tuesday.

The rig had been secured to a second tow vessel but when grounding was imminent, the second vessel was directed to abandon its tow line to avoid endangering the crew, the crisis command team said.

No one was hurt, the Coast Guard said.

When the Kulluk was removed from its final towline, it was 4 miles from land, a command team said late Monday.