(CNN) -- Three members of a U.S. Navy helicopter crew were killed after their helicopter went down in the waters off San Diego, California, a Navy spokeswoman said Wednesday. Rescuers are still searching for the two remaining crew members from the helicopter, which went down late Tuesday night, U.S. Navy spokeswoman Karin Burzynski said. No further details concerning the deaths were immediately available. Burzynski said the helicopter was operating from the USS Nimitz. The Navy received word that the helicopter went down around 11:30 p.m. Tuesday, she said. It crashed about 20 miles off the Mexican coast, the Navy said. Coast Guard spokesman Henry Dunphy told CNN earlier that Coast Guard helicopters and boats, as well as vessels from other agencies, were helping in the search.
NEW: Rescuers still searching for two people missing from Tuesday night crash . Coast Guard using helicopters and boats to search ocean for crew . Copter was doing training off coast of Mexico, near San Diego, when it crashed .