An offshore oil drilling platform 70 miles from New Orleans burned early Monday after explosions on it and an adjacent rig injured at least 10 crew members and left seven missing, the Coast Guard said. A helicopter and more than a dozen boats searched the Gulf of Mexico for the missing crew members. About 30 people were rescued from the burning rigs and surrounding water, according to the Coast Guard and the Atlantic Richfield Co. Flames on the second rig, connected to the burning one by a catwalk, were extinguished a few hours after they started Sunday evening.