The union representing some 70,000 Southern California grocery workers called a strike against Safeway Inc.'s SWY.N Vons and two rival supermarket chains responded on Sunday by locking out union workers. Picket lines organized by the United Food and Commercial Workers Union formed at stores from Los Angeles to San Diego, the first grocery strike in 25 years in the area, one of the nation's most populous and a key market for the chains. In response to the Vons strike, Albertsons Inc. ABS.N and Kroger Co.'s KR.N Ralphs, which are covered by the same master contract, locked out union workers from...