Former Olympic downhill gold medalist Bill Johnson, 40, was critically injured at Montana's Big Mountain resort on Thursday in a horrific crash during preparations for the upcoming United States Alpine nationals, say news reports. He was negotiating a series of turns during the race when he lost his balance at 45 mph and hit the snow. Johnson suffered severe head trauma and was transported via helicopter to Kalispell Regional Medical Center, where he underwent nearly four hours of surgery Thursday afternoon to reduce swelling in his brain. He also received treatment for a tongue injury. His condition is listed as stable but extremely critical. "It's a matter of God and time," U.S. Ski Team spokesman Tom Kelly told reporters.