Thousands of nurses across the country went on strike Friday morning, pushing for better patient care by demanding improved work conditions and higher pay.

About 6,500 National Nurses United members at 12 Tenet Healthcare hospitals in California, Arizona and Florida organized a 24-hour strike, which began at 7 a.m., to protest current nurse-to-patient ratios that they contend are burning out employees and making it difficult to provide the best possible care.

In Chicago, more than 2,000 nurses walked off the job after contract negotiations between National Nurses United and the University of Chicago Medical Center broke down on Wednesday night.

“We’re here to advocate for our patients,” said Yajaira Roman , an intensive care unit nurse who works for Tenet Healthcare’s Palmetto General Hospital in Hialeah, Fla. , and a member of the union’s bargaining committee. “We’re pretty much urging the hospital to invest in the nurses and take steps to strengthen our recruitment and retention of experienced nurses at the hospital.”