(CNN) -- Authorities scoured the national park around Washington's Mount Rainier on Sunday for a man they say fatally shot a park ranger and fled into the woods, a park spokeswoman said.
The suspect remained at large Sunday night, believed to be somewhere in the expansive park, Mount Rainier National Park spokeswoman Lee Taylor said.
Four to five feet of snow is on the ground, including about two feet of fresh powder, where the gunman escaped.
"There's a lot of snow on the ground, (and) it would be difficult to move through quickly," Taylor told CNN. "And it's heavily forested."
The bloodshed began with what the spokesman called "a normal traffic stop" around 10:30 a.m. PT (1:30 p.m. ET). But the suspect didn't heed a request to pull over, prompting a ranger to radio ahead requesting assistance.
Park ranger Margaret Anderson, 34, responded to that call and set up her patrol vehicle as a roadblock.
"When he (the shooter) arrived at that spot, he got out (of his car) and fatally shot her," said Taylor.
The suspect then ran into the spacious national park, whose border is about 50 miles southeast of Seattle. The park -- the centerpiece being the 14,410-foot Mount Rainier, which is considered an active volcano -- comprises 235,625 acres in the Cascade Range.
Entrances to the park were closed after the shooting. Taylor said that authorities were able to "evacuate most of the people ... safely," with more than 100 people "holed up in our primary visitor center" with food, water and five law enforcement officers standing guard.
"We don't want to try to have those people get to their vehicle and caravan down the park road where it could be dangerous, being sniped at by a gunman," the spokeswoman said Sunday night. "So for now, they are going to sit tight in the visitor center."
Anderson was the mother of a 4-year-old and 1-year-old and the wife of a fellow park ranger, according to Taylor.
A ranger at Mount Rainier for the past four years, Anderson "was on the job not for money or for glory, but out of a love for wild places and the national parks," said Taylor.
She is survived by her husband, who is also a park ranger, as well as a 4-year-old and a 1-year-old.
"She was a person with a quick smile, a very gentle person, a very competent ranger," said Taylor. "This gunman took the life of somebody who had a great deal to live for and was making great contributions to society by being a national park ranger."
CNN's Adam Shivers contributed to this report.