MOUNT RAINIER NATIONAL PARK, Wash. - A Mount Rainier National Park ranger was fatally shot following a New Year's Day traffic stop, and the 368-square-mile park in western Washington was closed as dozens of officers searched for the armed gunman over snowy and rugged terrain.

Pierce County Sheriff's spokesman Ed Troyer said late Sunday afternoon Benjamin Colton Barnes, a 24-year-old believed to have military experience and survivalist skills, was a "strong person of interest" in the slaying of Margaret Anderson. Authorities recovered Barnes' vehicle, which had weapons and body armor inside, Troyer said.

Authorities believed the gunman was still in the woods with an assault rifle. They asked people to stay away from the park, and for those already inside to leave.

Troyer said there were about 100 people hunkered down in lodges and cabins on the mountain. They were told to stay put because they could be in the line of fire. Armored vehicles were being brought in to ferry them safely out of the park.

"We do have a very hot and dangerous situation," he said.

KOMO-TV reported that Barnes was also a suspect in an early-morning shooting at a New Year's house party in Skyway, Wash., south of Seattle that left four people injured, two critically.

At Mount Rainier around 10:20 a.m. Sunday, a park service employee had unsuccessfully tried to pull a man over during a routine traffic stop.

Anderson set up a road block with her vehicle in the middle of the road, said park spokeswoman Lee Taylor. The man pulled up to Anderson about 11 a.m., jumped out, fired and ran off, she said.

Troyer said when authorities arrived they were also shot at, but no one else was hit. About 150 officers, including officials from the Washington State Patrol, U.S. Forest Service and FBI, were on the mountain. They had not made contact with the gunman and did not know where he was, Troyer said.

Authorities said earlier that Anderson's body had been removed from the park, but Troyer said police have been unable to get to her because of concern over potentially being in the line of fire.

Park superintendent Randy King said Anderson is a mother of two young daughters who has served as a park ranger for about four years. King said Anderson's husband also was working as a ranger elsewhere in the park at the time of the shooting.

"It's just a huge tragedy - for the family, the park and the park service," he said.

It has been legal for people to take loaded firearms into Mount Rainier since 2010, when a controversial federal law went into effect that made possession of firearms in national parks subject to state gun laws.

The shooting occurred on an unseasonably sunny and mild day. The park, which offers miles of wooded trails and spectacular vistas from which to see 14,410-foot Mount Rainier, draws between 1.5 million and 2 million visitors each year.