The U.S Coast Guard has said that an oil rig in the Gulf of Mexico that caught fire after an explosion on Tuesday night has now sunk. A search is continuing for 11 missing workers after the blast at the Deepwater Horizon rig. The other workers on the rig, off Louisiana, were evacuated to the U.S. The rig was carrying out exploratory drilling 84 kilometres south-east of the Louisiana port of Venice. The rig had been burning for 36 hours when it sank despite efforts to control the flames. On Wednesday it had been reportedly tilting about 70 degrees and threatening to topple over. There has been no sign of the 11 missing workers, despite rescue efforts by patrol boats through the night and an aerial search that resumed yesterday.