An oil drilling rig that had burned for 36 hours in the Gulf of Mexico sank on Thursday as hopes dimmed for 11 missing workers and the risk of a major oil spill loomed, officials said.

The fire went out as the Deepwater Horizon, operated by Transocean Ltd, sank below the surface at 10:21 a.m. CDT (1521 GMT), about 42 miles off the Louisiana coast.

The rig was drilling BP Plc’s Macondo project with 126 workers on board when it was ripped by an explosion and fire on Tuesday night. Some 115 workers escaped, including 17 helicoptered to New Orleans area hospitals with injuries.