MOUNT RAINIER NATIONAL PARK, Wash.

Tactical teams searched Mount Rainier National Park’s snowy terrain for an armed gunman suspected of killing a park ranger. Other officers used the cover of darkness early today to evacuate dozens of tourists who had been kept for their safety at a visitors center.

About 150 officers converged on the mountain park after ranger Margaret Anderson was shot to death Sunday morning, and searchers used an aircraft with heat-sensing capabilities to hunt from the skies.

Authorities believe the gunman was still in the woods, with weapons.

Pierce County Sheriff ’s spokesman Ed Troyer said that Benjamin Colton Barnes, a 24-year-old believed to have survivalist skills, was a “strong person of interest” in the slaying.

“We do have a very hot and dangerous situation,” Troyer said.

Safety concerns prompted authorities to keep about 125 tourists quarantined at a visitors center as the manhunt unfolded.

But early this morning, officers began escorting them in their cars out of the park.

Crews had initially planned to keep everyone in a basement with guards. But Troyer said it was determined to be “ better to do it ( evacuate) under the cover of darkness than daylight.”

All the visitors were expected to be out by 4 a.m.