A Pennsylvania man was the most seriously injured in the fall, which happened at about 7:20 a.m., Mount Rainier National Park spokeswoman Lee Taylor said.

Rescuers reported that one man slipped, dragging two other climbers and a mountain guide about 40 yards to a 20-foot-deep crevasse, Taylor said.

"The first two members of the team cleared the crevasse - in other words, they catapulted right over it," Taylor said. "But the final two members of the party fell into the crevasse and these were the two who were most severely injured."

Patrick Clemens of Bethlehem, Pa., suffered serious head trauma, along with a broken leg and possibly broken ribs, Taylor said.

An Oregon National Guard Blackhawk helicopter flew Clemens to Madigan Army Medical Center at Fort Lewis. The hospital, citing patient privacy rules, said it could not immediately release his condition. Clemens' age was not available.

A second Blackhawk flew Matthew Fisher, 42, of Vernon, N.J., to Harborview Medical Center in Seattle. Fisher was admitted to intensive care in serious condition with broken ribs and a liver injury, hospital spokeswoman Susan Gregg-Hanson said. He was alert and conscious Thursday afternoon, she said.

Also injured in the fall were Peter Bridgewater, 54, of Singapore, who suffered a dislocated shoulder; and John Lucia, 31, a mountain guide from Ashford who suffered a head injury, Taylor said. They were in satisfactory condition at Tacoma General Hospital, spokesman Todd Kelley said.

All four were evacuated by early afternoon from Ingraham Glacier at the 12,600-foot level of the 14,411-foot peak.

The men were trying to reach the summit with Rainier Mountaineering Inc., which holds the mountain's guide contract. The fall occurred near Disappointment Cleaver, along one of the most popular paths to the summit.

"This was the common route which is climbed every day," RMI founder Lou Whittaker said.

Other parties climbing with RMI guides were nearby and assisted with first aid and rescue efforts, and National Park Service rangers were dropped to the scene by helicopter, Taylor said.

It was the seventh climbing accident requiring a rescue in the past week on Rainier, which has seen one fatality this year, Taylor said.

Oregon National Guard Capt. Mike Braibish said Thursday's rescue was the second time this week the Guard's air ambulance units had been called to the mountain.