A Seattle hospital system shuttered two emergency rooms after thousands of its staff members refused to show up to work as part of a strike over concerns about chronic short-staffing and wages.

On Tuesday, employees filled the sidewalks outside of hospitals in the Swedish Medical Center system carrying signs with captions such as “patients before profits” and “united for our patients.” The strike will last three days, during which two of seven emergency rooms in the system have been closed to new patients.