More than 75,000 workers at Kaiser Permanente launched a strike Wednesday, with a coalition of unions alleging the health care system is engaging in unfair labor practices.
Employees in Virginia and Washington, D.C., walked off the job at 6 a.m. ET while those in California, Colorado, Washington and Oregon began striking at 9 a.m. ET, beginning the largest health care workers strike in U.S. history, the unions say.
Those in mid-Atlantic states will be striking for one day while those in western states will be striking for three days.
MORE: More than 7,000 nurses go on strike across 2 New York City hospitalsThe strike includes hundreds of positions, including nurses, emergency department technicians, pharmacists, optometrists, home health aides, medical assistants, dental assistants and more.
The Coalition of Kaiser Permanente Unions, which represents more than 85,000 workers, said Kaiser is experiencing a short-staffing crisis and that unsafe levels of staffing can result in long wait times, patient neglect and missed diagnoses.
Additionally, the Coalition said it's advocating for better medical plans for retirees as well as protections against work that is outsourced and subcontracted.
The Coalition and the nonprofit organization have been bargaining since April but were unable to reach an agreement before contracts expired on Sept. 30.
In a statement to ABC News Wednesday morning, Kaiser said bargaining was ongoing and some agreements had been reached.
"Both Kaiser Permanente management and Coalition union representatives are still at the bargaining table, having worked through the night in an effort to reach an agreement," the statement read. "There has been a lot of progress, with agreements reached on several specific proposals late Tuesday."
The statement continued, "We remain committed to reaching a new agreement that continues to provide our employees with market-leading wages, excellent benefits, generous retirement income plans, and valuable professional development opportunities."
By the evening, Kaiser announced that talks hadn't ended with a deal. The company said, though, in a statement that the two sides had reached some "tentative agreements" addressing union members' concerns, including wage increases across the board, an update to the performance-sharing plan, $25 minimum wage in California and $23 outside of the state, enhancing health and retirement benefits, and renewing the company's tuition assistance and training programs.
"We will coordinate with Coalition leaders to reconvene bargaining as soon as possible. We will work hard to reach an agreement so that together, we can all return to delivering on the mission of Kaiser Permanente for the benefit of our members, patients, employees, physicians, customers, and communities," read the company's statement Wednesday evening.
According to a statement from Caroline Lucas, spokesperson for the Coalition of Kaiser Permanente Unions, no new talks are scheduled.
“Frontline healthcare workers are awaiting a meaningful response from Kaiser executives regarding some of our key priorities including safe staffing, outsourcing protections for incumbent healthcare workers, and fair wages to reduce turnover. Healthcare workers within the coalition remain ready to meet at any time. Currently, the strike continues, and there are no sessions scheduled at this hour," her statement read.
Kaiser had said throughout the strike, all of its hospitals and emergency departments will remain open and contract workers have been hired to backfill striking employees.
MORE: Worker strikes are surging. Strains of technology may be to blame in part.The Kaiser strike comes amid several major labor actions in other sectors of the workforce. The United Auto Workers launched a strike on Sept. 15 against General Motors, Ford and Stellantis after failing to reach a contract agreement with the automakers.
Additionally, the Screen Actors Guild-American Federation of Television and Radio Artists (SAG-AFTRA) is continuing its strike against the Alliance of Motion Picture and Television Producers (AMPTP) which began on July 14.
The Writers Guild of America ended its strike against AMPTP last week after almost 150 days, securing better pay and regulations for the use of artificial intelligence in certain projects.
ABC News' Marilyn Heck contributed to this story.
