SAN FRANCISCO (AP) — Crews are tearing down a multimillion-dollar San Francisco house that is sliding down a hill, threatening other homes.

The three-story, mid-century house has separated more than a foot from the curb and has sunk more than a foot, says home owner Ronald Martell, who was on site Friday to oversee demolition work.

It's unclear what is causing the home to slide, although El Nino storms that have drenched the San Francisco Bay Area could be partly to blame. Martell said one neighbor has reported basement flooding, and there appears to be too much water on his property for the amount of rain that's fallen.

The city ordered five other homes— one on either side of Martell's house and three at the bottom of the hill behind his house_to hire engineers to show their homes are safe.

Records show the Martells bought the house for roughly $2 million in October. But the family hadn't moved in yet, pending a possible remodel.

It's been a bad week for Martell, a biotech chief executive who was attending his father's out-of-state funeral Tuesday when he learned the city had red-tagged the house, deeming it unsafe for occupation.

A neighbor initially texted Martell on Saturday to tell him about a crack in the driveway parallel to the curb. The next day the neighbor sent a photo.

On Monday, a contractor spotted a second crack. By Tuesday the city had red-tagged the house, deeming it unsafe for occupation, and informed Martell that his house was sliding_a shock since a buyer's inspection indicated nothing was wrong.

Martell and his family rushed back to San Francisco on Wednesday, a birthday he shares with his 13-year-old son, to meet with engineers. On Thursday, the city ordered an emergency demolition.

By then, the house had slipped 14 inches away from the curb and dropped 12 inches. The gaps have continued to grow.

William Strawn, a spokesman for San Francisco's Department of Building Inspection, said the city ordered an immediate teardown because of the "imminent public safety hazard."

Strawn said the cause of the unstable soil conditions is under investigation.

"We'd love to rebuild," Martell said. "The question is what's happening with the larger hillside and is there a water issue that needs to be corrected?"

Neighbor Mark Miller, whose home is unaffected, said seeing unsettled soil is unsettling.

"You don't expect your foundation to slip out from underneath you," he said.