A group of more than 500 Los Angeles Fire Department employees has sued the city of Los Angeles in an effort to prevent the vaccine mandate for city employees from being enforced.

The L.A. City Council approved a vaccine mandate for city employees last month, and Friday, 529 firefighters sued as a nonprofit collective called the Firefighters4Freedom Foundation. It follows a federal lawsuit filed last weekend by L.A. police officers in an attempt to overturn the requirement.

The firefighters are seeking a temporary restraining order to block the city’s vaccine mandate from going into effect “until a preliminary injunction hearing in this matter and further order of this Court,” the foundation’s attorneys wrote in a copy of the filing provided by Kevin McBride, one of the attorneys representing the firefighters.

The filing directly referenced the City Council’s vaccine mandate and the 13-0 vote that approved it, saying the firefighters are “pawns in a political chess match, ordered by thirteen politicians on the Los Angeles City Council to inject themselves with an experimental vaccine—over their objections—or lose their jobs.”

Coronavirus vaccines authorized for use in the U.S. have been proven safe and remarkably effective against the worst outcomes of the disease in studies of tens of thousands of people and in the tracking of their real-world performance.

Robert F. Kennedy Jr., son of the late senator and presidential candidate and a prominent anti-vaccine activist, is also listed as an attorney for the firefighters, pending approval to represent clients in California on this case alone.

On Twitter, Kennedy often pushes back against vaccine mandates.

The court filing lists the 529 firefighters who are part of the group, including Capt. Cristian Granucci, whose anti-vaccine mandate video went viral last month.

In the video, Granucci promised legal action if the vaccine mandate, which he called “total tyranny,” went forward.

“We will take the fight to you, the city of Los Angeles,” Granucci said.