Search and rescue teams in western Washington state are searching for a man who went hiking alone in the mountains on Saturday and never returned, authorities said.

Thomas Simonseth, 66, of Mount Vernon, left for a day hike up the Hidden Lake Trail, about nine miles east of Marblemount, and was expected to be back by 7 p.m. that same day, the Skagit County Sheriff’s Office said in a statement. No one has heard from Simonseth since he set off on Saturday morning.

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Simonseth’s wife, Rose, told Q13FOX that she was unable to sleep after her husband, a retired public school teacher, went missing.

"He was hiking alone, which he should have never done," she said. "That’s the hardest part."

Simonseth is a retired teacher who has been hiking for about a year, his wife told Q13FOX. (Skagit County Sheriff’s Office )

After Simonseth failed to return Saturday, two of his friends with mountaineering experience hiked up to the area to look for him, the sheriff’s office said. The pair spent the night in the hopes of resuming the search in the morning.

The sheriff’s office launched an official search with the assistance of search and rescue groups from Skagit and other counties at 7 a.m. on Sunday. 

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Day-long searches on Sunday and Monday both ended without locating Simonseth.

On Tuesday, multiple search and rescue teams returned to the mountain to conduct "a slow and methodical search" for the missing 66-year-old, the sheriff’s office said in an update.

Officials said they were hopeful that the conditions would be clear enough to deploy a helicopter in the search effort.

The sheriff’s office advised those wishing to help against going up the mountain to look for Simonseth.

"This is an active search with search and rescue teams from all over the area in a coordinated effort to locate Mr. Simonseth," the sheriff’s office said.