SAN FRANCISCO (AP) -- Southern California home values plummeted 24 percent during March, leaving prices at an almost four-year low amid the real estate market's deepening distress.

The median price of homes sold in a six-county region stood at $385,000 in March, a sobering turnaround from the previous year when values had reached a record $505,000, according to data released Tuesday by DataQuick Information Services.

Southern California homes haven't sold for so little since April 2004 when the region's median price stood at $380,000.

The median price represents the point where half the homes sell for more and half sell for less.

Tuesday's report covered Los Angeles, Orange, Riverside, San Bernardino, San Diego and Ventura counties -- a region that once ranked among the nation's hottest real estate markets as lenders aggressively lowered their rates and standards for qualifying for home loans.

As it turned out, many borrowers couldn't afford their mortgages after they adjusted upward from temporarily low rates. That has led to a wave of foreclosures that is prompting lenders to sell Southern California homes at sharp discounts and depressing the value of neighboring properties.

More than a third of the Southern California homes sold last month had been through a foreclosures at some point during the past year, according to DataQuick.

Riverside and San Bernardino counties -- a rapidly growing region known as the Inland Empire -- was particularly hard hit.

Foreclosures accounted for 56 percent of the sales in Riverside County, where the median price of a home fell 27 percent to $306,250. The erosion was even worse in San Bernardino County, where the median home price plunged 28 percent to $265,000.

Orange County remained Southern California's most expensive housing market with a median sales price of $506,000, but that was still 20 percent below last year's level.

The depressed market is prompting many prospective home sellers to stay on the sidelines until they see signs of an upturn, said Marshall Prentice, DataQuick's president.

"Often what we're left with, especially in inland areas, are sales driven by foreclosure or the threat of it," he said.