A paramedic-firefighter who disappeared last week always put others first, and authorities are asking the public to return the favor by calling police if they have any information that might help search crews scouring the rugged terrain of the Shenandoah National Park.

Nicole Mittendorff, 31, is an avid runner and tri-athlete whose family says might have been training on a trail near where her car was found Saturday, three days after anyone last heard from her.

"As you can imagine, the pain of not knowing where a loved one is can be unbearable," the woman's husband, Steven Mittendorff, said at the news conference.

Fairfax County Fire Chief Richard Bowers urged anyone with information to come forward.

"We want to focus on bringing Nicole home safely," he said at the news conference at the fire station where Mittendorff works, just across the Potomac River from the nation's capital. "This is our 911 call to the public."

Virginia State Police spokeswoman Corinne Geller said there is no indication of foul play.

About 100 search and rescue team members from several agencies continued to comb a steep, rocky and forested 10-square-mile section of the 300-square-mile Shenandoah National Park on Tuesday, park spokeswoman Sally Hurlbert said.

About 4 1/2 miles of five trails were closed for the search. Among them was the Whiteoak Canyon Trail, a large and popular path connected to Skyline Drive where the missing woman's Mini Cooper was found.

Crews have been searching during daylight hours since Saturday evening, Hulbert said, and there was no talk of quitting until Mittendorff is found.

"I've seen them search three weeks for people," Hulbert said.

Bowers lavished praise on Mittendorff, a three-year veteran of the fire and rescue department.

"She's dedicated, she's respected and she's well-liked among her peers and colleagues," he said.

A spokeswoman for the fire department said those who work closely with Mittendorff did not want to talk to the media.