Major oil producers said Sunday they would be evacuating workers from Gulf of Mexico platforms in the face of an imminent threat from Tropical Storm Isaac, NBC News reported. The storm could impact an area that produces 23 percent of 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. BP has already shut and evacuated four platforms, including Thunder Horse, the world's largest. 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. Anadarko Petroleum followed suit. According to Reuters Murphy Oil was evacuating its Thunder Hawk platform Sunday and would do the same with two other platforms on Monday and Royal Dutch Shell said it will shut down production and fully evacuate its platforms on Monday.