SAN FRANCISCO (AP) — Union workers at Raley’s supermarket chain, which operates more than 100 stores in California and Nevada, went on strike Sunday after last-ditch efforts to reach a new contract failed.

The strike, which marked the first against Raley’s in its 77-year-history, came after all-day talks Saturday. A midnight deadline was extended at the request of a federal mediator, but talks broke down around 2 a.m. Sunday, said Mike Henneberry, a United Food and Commercial Workers Union spokesman.