YOSEMITE NATIONAL PARK (CBS SF) – Rangers at Yosemite National Park are searching for a hiker who has been missing in the park for nearly a week.

Park officials said 24-year-old Alexander Sevier was last seen in Yosemite Valley on Wednesday. He had been staying in Housekeeping Camp and had spent the previous few days hiking around the Valley on his own.

Sevier is in the Navy and traveled to the park from Portsmouth, Virginia. He is described as 5-feet 6-inches tall, 126-pounds with black hair and brown eyes.

Search dogs and a California Highway Patrol helicopter have joined the search.

Park visitors who may have seen Sevier are asked to call 888-653-0009, 209-372-0608 or 209-372-0252.