The Florida Keys know what to expect from a big storm, and they're getting ready. Tourists have been warned to get out of town. Officials are taking no chances with just hours left to prepare before the storm makes landfall.

Major oil producers, including BP, Shell and Chevron, said Sunday they would be evacuating workers from Gulf of Mexico platforms in the face of an imminent threat of high surf and winds from Tropical Storm Isaac.

The storm could affect an area that produces 23 percent of total daily U.S. oil production and 7 percent of its natural gas output.

BP Plc said it will shut production at all of its Gulf of Mexico oil and gas platforms and evacuate all workers on Sunday in light of Isaac's westerly shift and forecasts that it could strengthen into a hurricane. BP has already shut and evacuated four platforms, including Thunder Horse, the world's largest. The company said Sunday it will shut its other three platforms.

Chevron, second to BP in Gulf oil production, said it would be evacuating some workers directly involved in oil and gas production from some of its platforms. "Chevron continues to closely monitor the projected path of Tropical Storm Isaac and has begun to evacuate some essential personnel from some offshore facilities in the Gulf of Mexico. Production has not been affected," the company said.

Anadarko Petroleum followed suit. "To ensure the safety of our workers and the protection of the environment, we are shutting in production and removing all personnel from our operated facilities in the eastern and central Gulf of Mexico," it said in a statement. Among the platforms it is shutting are: the Independence Hub, Constitution, Marco Polo, Red Hawk, Neptune and Gunnison.

Reuters said Murphy Oil was evacuating its Thunder Hawk platform Sunday and would do the same with two other platforms on Monday. Royal Dutch Shell said it will shut down production and fully evacuate its platforms on Monday, according to the news agency. Others who are evacuating workers include Marathon Oil and BHP Billiton.

The Bureau of Safety and Environmental Enforcement said the storm threat has so far shut down about a quarter of daily oil production in the Gulf and over 8 percent of its natural gas production.

Isaac is heading for the Gulf Coast, say forecasters, who predict the storm is likely to build into a Category 2 hurricane capable of sustained winds between 96 to 100 miles per hour. It could make landfall on the northern Gulf Coast by late Tuesday. The storm picked up strength as it passed over the warm waters of the Florida Straits after it lashed Cuba and left seven dead in Haiti.

Related story: Isaac strengthens, set to hit Gulf Coast as Category 2 storm

Memories are still fresh on the Gulf Coast over the BP Deepwater Horizon oil spill in 2010, which killed 11 platform workers and spewed millions of gallons of crude over three months into the environmentally sensitive Gulf of Mexico. The disaster, which was the largest marine oil spill ever, occurred after an explosion on the platform.

Reuters contributed to this report.

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