The Snohomish County Sheriff's Office says rescuers are searching for three experienced hikers who went off-trail east of Gold Bar.
Deputies say a woman called 911 late Sunday night to report that her 52-year-old husband, their son and one of his friends hadn't returned home as scheduled.
Search and rescue personnel and volunteers, along with a sheriff's office helicopter, headed out at about 5:30 a.m. Monday. Their vehicle was found at the Trout Creek Trail about two hours later.
The sheriff's office says officials are working with a cell phone service provider to try to pinpoint their location.
In a separate incident Monday morning, Snohomish County rescue crews came to the aid to a woman in her 50s who injured her knee in a fall along the Pacific Crest Trail. The woman activated a personal locator beacon monitored by a private company because she knew she wouldn't be able to hike out, and a sheriff's office helicopter picked her up near Mica Lake.