SEATTLE – Six climbers are missing on Mount Rainier, and a helicopter search for them was launched on Saturday, a National Parks spokeswoman said.

The missing group includes four clients of Seattle-based Alpine Ascents International and two guides. They were due to return from the mountain on Friday. When they did not return, the climbing company notified park officials, Park Ranger Fawn Bauer said.

“The last contact with them was at 12,800 feet,” Bauer said.

Mount Rainier, southeast of Seattle, stands at 14,410 feet and attracts thousands of climbers trying to reach its summit every year.

The search for the missing climbers is focusing on the northwest shoulder of the mountain at the Liberty Ridge area, near where they were last heard from, Bauer said. Saturday’s search includes a team of three climbing rangers on the ground and flyovers with a Hughes helicopter. An Army Chinook helicopter is on standby at Joint Base Lewis-McChord.

The last contact the group had with the climbing company was on Wednesday. They were scheduled to reach the summit of Mount Rainier on Thursday, with a day to climb down. The group is equipped with satellite and mobile phones.

A small weather front that brought snow flurries and hail to the mountain moved in on Wednesday, Bauer said. The weather has been clear since then.

Alpine Ascents’ director of programs, Gordon Janow, said he wasn’t ready to release information about the climbers. “Let’s hope they’re found and that it goes well,” he said.

Details – such as ages, gender or hometowns – for the climbers were not immediately available, Bauer said.

In a statement from the park, the guides were described as skilled.

In a blog post on the Alpine Ascents website Thursday, the post said the team had turned around at 13,000 feet during their attempt to reach the summit because of weather conditions. The blog post said all team members were well.