 Rescue crews are battling heavy snow as they try to reach a Marine Corps helicopter carrying five troops that went down in the mountains near San Diego. The five Marines were aboard a CH-53E Super Stallion helicopter that departed from Creech Air Force Base, northwest of Las Vegas, where they were doing a routine training flight, defense officials said. They were returning home to Marine Corps Air Station Miramar in San Diego when the aircraft was reported overdue, teams in several states began a search and the aircraft was located by civil authorities in Pine Valley, California, about 45 miles east of San Diego. The third Marine aircraft wing said in a statement it is managing search and rescue efforts and using ground and aviation assets to locate the aircrew in coordination with the San Diego County Sheriff's Department and multiple federal, state and local agencies. The third Marine aircraft wing is managing search and rescue efforts through the Wing Operations Command and using ground and aviation assets to locate the aircrew in coordination with the San Diego County Sheriff's Department and multiple federal, state and local agencies, a press release from the Marine Corps said. Weather conditions in the area were a mixture of snow and rain.