An avalanche at Mammoth Mountain early Saturday forced the closure of the popular ski area and triggered search and rescue efforts, officials said. There were no reports of serious injuries or missing people, but emergency crews were activated, officials said.{snip} "Shortly before the slide, that area was very crowded," Maynard said. "Essentially, the top of the mountain came loose in a major avalanche."{snip} "We hiked about 15 minutes to the parking lot, where local emergency mayhem had broken out," Williams said. "There were people trying to get out any way they could; some were waiting for buses, others were sharing...