SAN DIEGO , California ( CNN ) -- More than 100 homes in an upscale San Diego community were evacuated after a landslide about 60 yards wide pulled the earth from beneath a three-lane road and some of the multimillion-dollar homes that adorn it . Gina Yarbrough sent this picture of the road that collapsed in Wednesday 's landslide . Mayor Jerry Sanders declared a state of emergency , asking California and the federal government to help the La Jolla community recover from the Wednesday landslide . As of Thursday morning , he had already received offers of aid from legislators , the governor 's office and the White House , he said . Officials warned for at least two weeks that the ground was shifting beneath the hillside community along Soledad Mountain Road . Holes were drilled into the unsettled hillside to investigate the cause and magnitude of the shift , which earlier ruptured a water line , and according to some media reports , began cracking Soledad Mountain Road in July . On Wednesday , a 20-foot-deep chasm opened beneath the road and homes . Holli Weld told San Diego 's KGTV that she was walking her son to preschool when the street collapsed . Watch a resident recall how he had to grab his dogs and run » . `` The street was sinking before our eyes , '' she said . Authorities told KGTV that most residents were at work and only seven people were in their homes when the landslide occurred . Evacuated homeowner Russell Moore told CNN he remembers hearing the earth `` groan '' in what he called a `` slow avalanche . '' `` The asphalt that should be under my feet was 8 feet in the air , '' Moore said . `` We watched the trees snapping and cracking and more boulders come down to our feet and we were witnessing this move . '' See photos of the hole the landslide left in La Jolla » . At least 111 homes were evacuated , but Sanders said residents would be allowed to return to 75 of those houses by early Thursday morning . Several homes were damaged and at least one was destroyed , according to media reports . Nine homes are `` red tagged , '' meaning no one is allowed to enter them , and 27 more are `` yellow tagged , '' which means residents can return for necessities , but can not stay , Sanders said . According to the San Diego Union-Tribune , the landslide downed power lines and caused a minor gas leak . More than 2,400 customers were briefly left without electricity , but most residents had their power restored by Thursday , KGTV reported . The Red Cross opened a shelter at La Jolla High School . Deputy city engineer Robert Hawk told the Union-Tribune that the hillside has slowly been slipping for years because the soil is unstable . Landslide incidents in the neighborhood date back to the 1960s , Hawk told the newspaper . Pat Abbott , a retired geological sciences professor at San Diego State University , told the Union-Tribune that Mount Soledad is made up of weak layers of rock and that the culprit in the landslide is nature . `` Gravity pulling on the incline is pulling down masses of earth and those masses of earth have houses on top of them , '' Abbott told the paper . `` It 's a geologically bad site and should not have been built on to begin with . '' E-mail to a friend .
San Diego mayor declares state of emergency ; White House , governor offer aid . Officials were investigating the shifting earth in the area for weeks . Residents can return to 75 of the 111 evacuated homes Thursday , mayor says . `` We watched the trees snapping and cracking , '' says one evacuated resident .