ST. MORITZ, Switzerland -- U.S. bobsledder Joe Sisson was seriously injured during a practice session on the Cresta Run in this Swiss resort, officials said Tuesday.

Sisson suffered serious head injuries during a training run on the course Monday, and was taken to hospital by helicopter, said Graubuenden cantonal (state) police.

The 21 year-old was in the intensive care unit of the hospital in the town of Chur, police said in a statement late Tuesday. His condition was critical, they said.

Sisson, of Evanston, Wyo., was preparing for the World Junior Bobsled Championships, which take place on the Cresta Run Thursday.

"I'm in shock, half this town is in shock. They've been anxiously awaiting the Olympics and now we're in shock," said Paul Skog, a family friend from Evanston, which is 80 miles east of Salt Lake City, site of the Winter Olympics.

Sisson's father, Bryan Sisson, mother, Lynn Leininger, and stepfather, Michael Putnam, were on their way to Switzerland, Skog said. A fund-raising drive has been started to help the family with medical and travel expenses, Skog said.

Sisson graduated from Evanston High School in 1999. He was introduced to bobsledding by Skog, his next-door neighbor and promoter for the Jamaican bobsled team, which has made Evanston a home base while training at Park City, Utah.

The team, the inspiration for the Disney movie, "Cool Runnings," helped Sisson pursue his dreams.

"It's no longer a Disney movie script," Skog said. "The whole thing changed on me yesterday."

Sisson was training for the two-man bob with brakeman Jamey Sperle when their sled overturned on Horse Shoe bend, a third of the way down the course, during their first practice run.

Sperle was thrown clear and was unhurt, but Sisson remained stuck in the sled, which continued upside down to the final bend of the 1,200-meter (3,937-foot) run.

Sisson finished fifth in the U.S. Olympic trials in November but did not make the team for the Salt Lake City games. He had planned to participate in the Olympics as a forerunner, which is a bobsledder that tests the track before the race.