ANCHORAGE, Alaska -- Dozens of National Guard troops have arrived in Cordova to help the Alaska fishing town dig out from massive snows that have collapsed roofs, trapped some people in homes and triggered avalanches.The city is used to snow, but not like this season's blanketing.The Guard reported more than 18 feet of snow has fallen in the past weeks, although the National Weather Service did not immediately have a measurement."There's nowhere to go with the snow because it's piled up so high," said Wendy Rainney, who owns the Orca Adventure Lodge. A storage building for the lodge -- which offers fishing trips, hiking, kayaking and glacier tours -- partially collapsed under the weight of the snow, she said."This is more quantity than can be handled."At least three buildings have collapsed or partially collapsed and six homes are deemed severely stressed by heavy wet snow, officials said.The drifts are 12 to 14 feet high, but most roofs in town have been shoveled, said Chris Dunlap, a Cordova resident who was manning an empty Red Cross shelter early Monday."It's a lot of snow. I've lived here 33 years and this is the most snow I've ever seen," she said by phone. "The thing I'm impressed most with is we haven't had any injuries. Maybe a few back strains from all of the shoveling. But we have a very, very efficient, professional emergency staff here."The city has set up a shelter at a local recreation center but said people leaving homes in avalanche-risky areas have been staying with other residents. Cordova spokesman Allen Marquette said the town also was ready to set up a pet shelter if necessary.The town issued a disaster proclamation last week after three weeks of relentless snow overwhelmed local crews working around the clock and filled snow dump sites."We had no alternative but to declare an emergency," Cordova Mayor Jim Kallander said. "It became a life-safety issue."Responders said Sunday that rain fell overnight, making for a slippery, treacherous mess in the Prince William Sound community of 2,000 year-round residents. The region has been pummeled by snow, but Cordova is of particular concern because there is no road access to the town, only boat and plane passage, said Maj. Gen. Thomas Katkus, adjutant general of the Alaska National Guard.There have been no reported injuries, but bad weather has prevented the Guard from flying to the town, 150 miles southeast of Anchorage.More than 70 Guard members arrived in Cordova via state ferry Sunday. About 50 of them will help clear roofs, roads, boats. The rest will provide other assistance. Three state emergency workers were already in town to help with emergency response planning. The state also is working on bringing in more heavy equipment to Cordova.Katkus said Guard members will be on hand for up to two weeks. "This is an ongoing operation," he told reporters Sunday.An avalanche brought snow and debris down on a section of the Copper River Highway, the 12-mile link from the town to the local airport. State transportation officials said a secondary road was opened to two-lane traffic while crews cleared the highway Sunday.Another storm that started Saturday also brought rain, which soaked into the snow, weighing it down.Classes were to begin later than usual Monday, but officials said students should go only if parents are comfortable with them venturing out.Some roads have been cleared, but residents also are being creative, traveling on foot and by skis and snowshoes, officials said.The National Weather Service said the snow depth at the airport measured 59 inches before the rain fell, weighing the level down to 47 inches. Monday was supposed to be clear before another system moves in Tuesday, bringing more snow and rain, as well as winds as strong as 40 mph."This break in the weather is very critical and very fortunate," meteorologist Don Moore said.------Associated Press radio reporter Ed Donahue in Washington contributed to this story.