LOS ANGELES (AP) _ Thirty-seven striking University of Southern California workers and supporters, many in caps and gowns, were arrested Friday for blocking streets near the campus on graduation day.

Police arrested 22 demonstrators, most of them USC food service and housing employees who went on strike April 29, after they sat down and held hands.

Supporters held a banner reading ``Justice, Respect, Dignity.''

Thirty minutes later at another corner of the campus, a sit-down protest was broken up with the arrest of 15 people.

Police said the protesters failed to obey a dispersal order. They were taken to a police station, cited and released.

On campus, students, families and friends gathered for 8:30 a.m. commencement ceremonies featuring a keynote address by entertainer Bill Cosby.

The demonstration was staged by Local 11 of the Hotel Employees & Restaurant Employees union, which struck the university over job security. The workers have been without a contract for three years.