A 27-year-old Johnsburg man who was a seasonal employee at Glacier National Park in Montana was reported missing early Monday, park officials said.

Park dispatch received a call at 2 a.m. Monday alerting them that Jacob Rigby, a 2002 graduate of Johnsburg High School, was overdue from a personal day hike in the park and his supervisor notified park rangers that he did not show for work at his scheduled time later that morning, the National Park Service said in a news release.

Rigby's brother, Dave Rigby, said his brother's girlfriend knew he had gone on a hike and became nervous when he hadn't returned as planned.

Rangers have located his vehicle at the southern end of the park, along Montana Highway 2.

Dave Rigby said that his brother had been working on and off in the park for several years, most recently serving on the exotic plant team. He received a degree in geology from the University of Illinois at Urbana-Champaign.

Officials think that Rigby was hiking an extreme mountain traverse with challenging terrain in the Soldier Mountain, Sheep Mountain, Brave Dog Mountain, Mount Despair and Eagle Ribs Mountain areas in the southern end of the park, but he may be anywhere in the vicinity.

Dave Rigby said he exchanged Facebook messages with his brother last week, but wasn't aware of this most recent trip. This wasn't unusual, though.

"He goes hiking on his time off all the time," Dave Rigby said, adding that his brother has received extensive training through the National Park Services.

Rigby is described as an avid and skilled hiker who is familiar with the park, possesses excellent scouting capabilities and enjoys hiking off trail. He is 6 feet tall with brown, short and curly hair. He is of medium build and suspected to be wearing a blue t-shirt, blue Patagonia hiking shorts, white/silver Mamut daypack, size 10 La Sportiva boots with Vibram soles, and possibly gators.

Dave Rigby thinks Jacob likely became lost or injured on his hike.

"He keeps to himself, but he's a really smart guy," Dave Rigby said on the phone in Montana. "We're not overly concerned that he did anything wrong. We're just thinking the he might have slipped and rolled his ankle and can't walk, or took a wrong turn."

Anyone that may have been in the area, in the Ole Creek or Park Creek Drainages, on Sunday and may have seen Rigby is encouraged to contact park dispatch at 406-888-7800 or 406-888-5800.