NEW : U.S. divers plan to enter water on Friday , official says . Diver lost consciousness while underwater during rescue and could not be revived . Rescue teams searching for 58 North Korean sailors missing after Wednesday explosion . 46 seamen were rescued soon after blast ; no bodies or survivors found since then .
NEW : U.S. divers plan to enter water on Wednesday , official says . Diver lost consciousness while underwater during rescue and could not be revived . Rescue teams searching for 46 South Korean sailors missing after Friday explosion . 58 seamen were rescued soon after blast ; no bodies or survivors found since then .