KHALLID TANVEER/AP

Pakistani army soldiers in a helicopter rescue families stranded by floodwaters Thursday in the central Pakistan town of Sanawan. U.S. Army choppers flew their first relief missions in Pakistan's flood-ravaged northwest Thursday, airlifting hundreds of stranded people to safety from a devastated tourist town and distributing emergency aid. In the country's south, authorities began evacuating 500,000 people as the worst monsoon rains in decades threatened new destruction.