Editor's note: This updates with information that shooter fired upon other rangers to prevent them from reaching Ranger Anderson, and that nearly 100 visitors and staff are being kept inside the Jackson Memorial Visitor Center at Paradise.

A 34-year-old Mount Rainier National Park ranger was shot and killed in the line of duty Sunday as she tried to apprehend a man who fled a check stop at Paradise. Fellow rangers were prevented from reaching the downed ranger for about 90 minutes as the shooter pinned them down with gunfire.

Park spokesman Kevin Bacher said Margaret Anderson, a law enforcement ranger, was shot shortly after 10 a.m. Pacific at a roadblock set up to apprehend the unidentified man.

"He shot her, and then apparently left the vehicle, and when other law enforcment arrived, he started shooting at them, which kept them from reaching Ranger Anderson," said Lee Snook, another park information officer.

"It was about 90 minutes before they could reach her.”

Whether Ranger Anderson, who was married and had two young children, died on the scene or later at a hospital was not immediately known. Details on the shooting were sketchy.

Ranger Margaret Anderson. NPS file photo.

While there were reports a rifle was involved, neither Mr. Bacher nor Ms. Snook could not confirm that. Nor could they say why the initial traffic stop was attempted.

"One of our rangers attempted to make a vehicle stop near Paradise, and the suspect fled in his car," Mr. Bacher said. "A roadblock was set up about a mile below Paradise, at a place called Barn Flat, and apparently shots were fired."

In Washington, D.C., Interior Secretary Ken Salazar said he was "deeply saddened by the tragic, horrific and cowardly murder today at Mount Rainier National Park."

"The Department of the Interior and the National Park Service will do everything possible to bring the perpetrator of this crime to justice and to ensure the safety of park visitors and other park rangers," the secretary said in a prepared statement. "This tragedy serves as a reminder of the risks undertaken by the men and women of the National Park Service and law enforcement officers across the Department every day, and we thank them for their service. My thoughts and prayers are with Margaret's family in this difficult time."

Numerous emergency vehicles were at the park's Longmire administrative building Sunday evening as a manhunt continued in connection with the fatal shooting of a park ranger. NPS webcam shot about 4:40 p.m. PST.

Back at Mount Rainier, possibly lending help to the search was the more than 50 inches of snow on the ground at Paradise, snow that makes it "hard to cover your tracks," Mr. Bacher said.

Aiding park rangers in the manhunt were FBI and local law enforcement personnel. Officials closed off access to the park through its Nisqually Entrance, placing roadblocks on the road that leads from  Ashford, Washington, to Longmire and on to Paradise inside the park.

All other park roads have been closed by winter's snows. Visitors already at Paradise Sunday morning to cross-country ski, snowshoe, or sled were moved into the Jackson Memorial Visitor Center for their safety. Ms. Snook said about 86 visitors and 13 staff were being held there.

Roughly 100 people were being kept inside the Jackson Memorial Visitor Center Sunday evening as a manhunt continued for a suspect wanted in connection with the killing of a park ranger. NPS image taking from webcam about 4:40 p.m. PST.

“They have food and shelter for the evening, if that’s necessary," the spokeswoman said. "We're just trying to keep them safe. Where the visitors would have to drive (to leave the park) is right by where the assailant was last seen."

Over the years more than 200 Park Service staff have died or been killed on the job. Kris Eggle, a ranger at Organ Pipe Cactus National Monument, was shot and killed in the line of duty in 2002 while pursuing suspected drug runners who were armed with AK-47s.