More than 400 nurses at St. Mary of Nazareth Hospital in Chicago’s Ukrainian Village neighborhood walked off the job Thursday in a one-day strike, as they attempt to reach their first contract with Prime Healthcare, the California-based for-profit company that purchased the hospital last year.

The nurses, represented by an affiliate of National Nurses United, say they are fighting for safe staffing levels and adequate supplies. Daisey Moreno, a nurse at St. Mary of Nazareth, said the union has been unable to get Prime to come to the bargaining table. She said the hospital is short on supplies and needs better staffing.

We are not able to provide the basic essentials to provide care for patients, Moreno said. Sometimes patients are critical and the more critical they are the more close attention they need from nurses.

A hospital spokesperson said in a statement that the nurses went on strike before the parties have even had an opportunity to begin negotiations and disputed the claim that the hospital has refused to bargain. The strike was not expected to disrupt patient care, according to the statement.

The one-day strike at St. Mary of Nazareth was one of four taking place at Prime hospitals on Thursday, with additional strikes in California and Nevada. About 30 miles south, nurses at Olympia Fields Hospital also protested Thursday over what the union describes as retaliation against nurses for participating in union activity. Prime recently suspended six nurses at Olympia Fields and one nurse at Saint Francis Hospital in Evanston.

Nurses at Olympia Fields and Saint Francis filed petitions August 24 with the National Labor Relations Board to hold union elections, with votes scheduled for later this month. Nurses at Olympia Fields plan a one-day strike on September 15.

The alleged retaliation comes months after the union contended that Prime fired six nurses for participating in union activity at St. Mary of Nazareth earlier this year. Karlie Thorn, one of the nurses fired in that round, joined her former colleagues on the picket line Thursday. She said she was fired after handing out leaflets off hospital property before her shift and was told she was being terminated for trespassing.

Prime also announced this week that it plans to suspend obstetric care at three of its Illinois hospitals and centralize those services at St. Mary of Nazareth and Olympia Fields.