A new leak has been discovered in the area where an oil platform exploded and sunk into the Gulf of Mexico, the U.S. Coast Guard reported Thursday.

The spill is much worse than authorities previously thought. Coast Guard Rear Adm. Mary Landry said 5,000 barrels a day are leaking from a sunken oil rig, as opposed to the 1,000 barrels that was originally estimated.

The news comes after the Guard began a controlled burn of the massive spill in an effort to slow its progression toward the U.S. shoreline. The burn began late Wednesday in an area 30 miles east of the Mississippi River Delta.

Click play for an update with CBN News Reporter Efrem Graham.

Homeland Security Secretary Janet Napolitano said the government has offered to have the Department of Defense to help contain the spill.

"It has become clear after several unsuccessful attempts to determine the cause" that agencies must supplement what's being done by the company," she said.

The oil could begin washing ashore the Louisiana coast by Friday night.

"When you've got an oil leak like this, you use every tool in the toolbox to keep it offshore," said Edward Overton, a professor emeritus of environmental sciences at Louisiana State University in Baton Rouge. "If it gets to shore, it's going to coat everything with this sticky, gooey stuff and create a tremendous, awful mess."