SAN DIEGO – A landslide swept away a chunk of an upscale hilltop neighborhood Wednesday, destroying a home, damaging five others and opening up a 50-yard chasm in a four-lane road.

Forty-six homes in the La Jolla neighborhood were evacuated but no one was hurt in the collapse, which occurred the morning after city officials warned residents of four homes not to sleep in them because the land might give way.

The collapse shortly before 9 a.m. toppled power lines and left a 15-foot-deep ravine of crumpled pavement. Orange traffic cones and sections of big concrete pipes sat in the fissure slashing across the wide boulevard.

Holli Weld was walking her son to preschool when the street collapsed.

“It was sinking as I was walking by,” she said. “The street was sinking before our eyes.”

Authorities said most residents had gone to work and only seven people were inside the homes when the collapse occurred.

The landslide cut a cone shape through the neighborhood of million-dollar homes, said Robert Hawk, a city engineering geologist. Six homes were damaged or destroyed and two others were in danger, but the problems appeared to be contained.

“It is fairly well-defined and localized,” Hawk said.

Forty-six homes on the hilltop road and two streets below were evacuated, according to the city fire-rescue department.

Electricity was initially cut off to 2,400 customers but restored to 2,000 within two hours, according to San Diego Gas & Electric Co. Gas was cut off to about a dozen customers.

A firm hired by the city last month was in the area this week after a large section of slope on Mount Soledad began to slip, Hawk said. The city began noticing cracks on Soledad Mountain Road in July and water and gas main breaks in August.

Officials first became concerned about a landslide three or four weeks ago.

The city sent letters to residents Monday and Tuesday warning residents, and the outside firm hired by the city recommended Tuesday that four homes be evacuated, Hawk said.

At least three significant hill slides have occurred in the area between 1961 and 1994, including a major failure in 1961 that destroyed homes under construction.