Two men have been injured -- one critically, in an avalanche in Summit County. A spokeswoman at Saint Anthony Hospital in Denver says a 28-year-old man injured in the avalanche is in critical condition. Another man is being treated for a knee injury at a Breckenridge hospital. Summit County authorities say they were alerted at about 5:30 this evening. The avalanche occurred near Hoosier Pass on Quandry Mountain. The area is south of Breckenridge. The Colorado Avalanche Information Center says the snowpack in many areas is unstable because of all the new snow that has fallen in the mountains.