SAN DIEGO -- v class="polopoly_embed" data-attribute="embed_code">

Rescuers were battling heavy snow Wednesday to reach a Marine Corps helicopter carrying five troops that went down in the mountains outside San Diego.

The CH-53E Super Stallion helicopter -- the largest helicopter in the military, designed to fly in harsh conditions -- had gone missing as an historic storm dumped heavy snow and record rain over California.

Civilian authorities searching on ground and by air located the aircraft just after 9 a.m. Wednesday near the mountain community of Pine Valley, about a 45-mile (72-kilometre) drive from San Diego, but snowy conditions were making it challenging to gain access on the ground, officials said.