A rescue helicopter lifted 20 Northern Arizona University students and staff out of an area on the North Rim of the Grand Canyon, according to the Coconino County Sheriff’s Office. The operation began following a call from a representative of the university who reported two of the university’s vans that were carrying 16 students, two university staff members and two graduate assistants were stranded in snow-covered and impassable dirt roads.

The group had been camping in the area for several days and their vehicles became stuck in the snow when they attempted to leave the area on Monday. While they were able to free the vehicles, it became apparent that the roads were impassable, which eventually led to the call to the authorities. But weather conditions prevented an immediate rescue. In the meantime, authorities were able to contact the group intermittently through cell phones and satellite texting equipment. In lieu of a rescue, the group of students and staff were instructed to drive as far east as possible and to take shelter inside their vehicles. Weather reports indicate snowfall between 18 and 24 inches in the area.

On Tuesday morning, an Arizona Department of Public Safety was then flown into the area to survey the situation. And after the pilot determined it was safe, the rescue operation began at 1 p.m. local time with the pilot airlifting the stranded students and faculty three at a time. The group was flown to a parking lot at neighboring Arizona town, Jacobs Lake.

The students were participating in a Parks and Recreation Management Outdoor Education and Leadership program, according to a university official. The field trip started last Wednesday and was scheduled to conclude on Monday.

Authorities credited the stranded students were their wilderness knowledge and preparation that helped ease rescue efforts.

"It was nice that they were calm and knew what they were doing," Gerry Blair, a sheriff’s office spokesman, said according to AZ Central. "This group was prepared."