Robot vessels cap Louisiana oil leak
Robotic submersibles are being used to try to stop a fast-flowing oil leak nearly a mile (1.5km) below the surface in the Gulf of Mexico.
Some 1,000 barrels (42,000 gallons) of oil a day are spewing from a damaged well, after a drilling rig exploded and sank off the Louisiana coast last week.
British oil company BP, which leased the rig, said the "first-of-its-kind" attempt would take 24 to 36 hours.
There are fears of an environmental disaster if the mission fails.
Conservation experts say the oil leak has the potential to damage beaches, barrier islands and wetlands across the coastline.
For now, the weather conditions are keeping the oil away from the coastline and it is hoped the waves will break up the heavy crude oil, allowing it to harden and sink back to the ocean floor.