Horizon oil well spill

Photograph: Gerald Herbert/AP

Boats with oil booms try to contain oil spilled from the explosion and collapse of the Deepwater Horizon rig in the Gulf of Mexico. 

The Coast Guard says a sheen of oil that's been covering an area in the Gulf of Mexico since an oil rig exploded off the Louisiana coast is growing.

Eleven people have been missing and presumed dead since the rig exploded and sank last week about 50 miles (80 kilometers) off the southern state's coast.

Coast Guard Petty Officer Erik Swanson said that as of Tuesday morning, oil that leaked from the rig site was spread over an area about 48 miles (77 kilometers) long and 80 miles (129 kilometers) wide at its widest. The borders of the spill were uneven, making it difficult to calculate how many square miles are covered.

Swanson said the weather was currently in their favor, as the wind was blowing the oil away from shore on Tuesday, But Swanson said the winds could shift later in the week.