VERLOT, Wash. -- The body of the 13-year-old Mukilteo girl who was swept away by an avalanche in a remote area of Snohomish County on Friday has been recovered.

Searchers recovered the body around 1:30 a.m. on Saturday.

Search officials said seven kids and an adult were on a day hike, headed toward Lake 22 on Mt. Pilchuk when weather turned bad.

The group turned around and started to descend a steep hill in single file when the avalanche hit.

Four of the children were swept away. A boy dug himself out and two girls safely pulled out by the group. A fourth child was nowhere to be found.

The group spent an hour searching for the missing girl, using their hiking poles to dig through the snow. When they could not find her, they hiked 2.7 miles to the ranger station and alerted authorities.

About 24 members of the Snohomish County Volunteer Search and Rescue team shut down the hiking area and began combing the back country.

At around 10:30 p.m. on Friday, the team found the girl's body.

Sheriff's spokesperson Rebecca Hover said the exact cause of the avalanche is not known, but officials do not believe it was caused by people.

Hover said a possible cause may be a cornice failure, which means a swell of snow may have been drifted over a peak or a ridge by the wind, then pushed downhill by heavy rains and the weight of the snow itself.

Rescue workers believe the avalanche started at 500 feet above the area where the group was walking.

The girl's name has not been released.

The trail is now reopen, but avalanche officials urge all those who plan to use the trail to be very, very careful.