SAN FRANCISCO (CBS SF/AP) — Thousands of University of California medical workers began a three-day strike Tuesday against hospitals, clinics and campuses including at UC-San Francisco that has prompted the rescheduling of thousands of surgeries and outpatient appointments.

Picket lines went up at UC San Francisco Medical Center Parnassus, UC San Francisco Medical Center Mission Bay and UC Berkeley. Workers also walked off the job at four other UC medical centers in Los Angeles, San Diego, Irvine and Davis.

More than 4,000 appointments and 241 surgeries were rescheduled at UCSF medical center and its two associated clinics, said Sheila Antrum, chief operating officer.

The workers, represented by American Federation of State, County and Municipal Employees Local 3299, say UC’s outsourcing practices have created “alarming patterns of inequality” and are damaging services.

Contract companies pay workers less and offer little to no benefits, union leaders said, threatening union jobs.

“We’ve bargained in good faith for over a year to address outsourcing at UC because it creates unequal and insecure circumstances that workers must struggle with every day,” AFSCME Local 3299 President Kathryn Lybarger said.

The walkout involved more than 15,000 patient care technical workers, including radiology technicians, respiratory therapists, pharmacy workers, laboratory workers and others but not nurses.

Another 24,000 other union workers, ranging from truck drivers to gardeners and cooks, were striking in sympathy, said John de los Angeles, spokesman for the American Federation of State, County and Municipal Employees Local 3299.

A previous 3-day strike in May by university service workers prompted 53,000 workers to walk off the job.

UC officials maintain AFSCME leaders are spreading false information about union employees being displaced. They said that over the past five years UC systemwide, the number of patient care employees has increased by 2,450 workers, and spending on campus service contracts has remained flat.

“It is unfortunate that AFSCME leaders still have yet to glean a simple lesson from their May demonstration: their combative stance is harmful and ineffective,” Claire Doan, spokesperson for the UC Office of the President, said.

During the strike this week, a limited number of employees will continue to work, per an agreement worked out with the university, union officials said.