OVER THE GULF OF MEXICO (AP) — It’s a hellish scene: Giant sheets of flame racing across the Gulf of Mexico as thick, black smoke billows high into sky.

This, though, is no Hollywood action movie. It’s the real-life plan to be deployed just 20 miles from the Gulf Coast in a last-ditch effort to burn up an oil spill before it could wash ashore and wreak environmental havoc.

The Coast Guard late Wednesday afternoon started a test burn of an area about 30 miles east of the delta of the Mississippi River to see how the technique was working. Crews planned to use hand-held flares to set fire to sections of the massive spill. Crews turned to the plan after failing to stop a 1,000-barrel-a-day leak at the spot where a deepwater oil platform exploded and sank.

A 500-foot boom was to be used to corral several thousand gallons of the thickest oil on the surface, which will then be towed to a more remote area, set on fire, and allowed to burn for about an hour.

If the hourlong test burn was successful, rig operator BP PLC was expected to continue the oil fires as long as the weather cooperated. The burns were not expected to be done at night.

About 42,000 gallons of oil a day are leaking into the Gulf from the blown-out well drilled by the Deepwater Horizon oil rig. Eleven workers are missing and presumed dead. The cause of the explosion has not been determined.

Greg Pollock, head of the oil spill division of the Texas General Land Office, which is providing equipment for crews in the Gulf, said he is not aware of a similar burn ever being done off the U.S. coast. The last time crews with his agency used fire booms to burn oil was a 1995 spill on the San Jacinto River.

“When you can get oil ignited, it is an absolutely effective way of getting rid of a huge percentage of the oil,” he said. “I can’t overstate how important it is to get the oil off the surface of the water.”

The oil has the consistency of thick roofing tar.

When the flames goes out, Pollock said, the material that is left resembles a hardened ball of tar that can be removed from the water with nets or skimmers.

“I would say there is little threat to the environment because it won’t coat an animal, and because all the volatiles have been consumed if it gets on a shore it can be simply picked up,” he said.