A Los Angeles firefighter is under internal investigation after sharing a video of himself ranting against vaccine mandates while in department uniform.

Los Angeles Fire Department Capt. Cristian Granucci posted a video of his thoughts on vaccine mandates and required testing online Monday, and a repost of the original video on YouTube had drawn more than 15,000 views as of 10 p.m.

In the 12-minute video, Granucci called the requirement for LAFD employees to be vaccinated or face twice-weekly testing “total tyranny” and said he’s “done being silent on this matter, and so are many of our members.”

After the Aug. 18 L.A. City Council vote to require COVID vaccinations for city employees, a vaccine mandate requires only the mayor’s signature to be enacted, and the LAFD’s “Oath and Affirmation require all members to obey the Laws and Ordinances of the City of LA,” according to the LAFD.

Granucci criticized department and union officials for “play[ing] politics with this” and threatens legal action if the mandate is enforced.

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

Now, the 31-year veteran of the fire department may face disciplinary action, according to a statement from the LAFD.

“While we respect the individual’s right to his opinion, he is not authorized to speak on behalf of the Department, the department said. “The individual is in uniform and appears to be on duty, thereby giving the impression that he is speaking in an official capacity.”

LAFD said it became aware of the video Monday morning and subsequently spurred an investigation into Granucci’s actions, which may lead to disciplinary review.

LAFD Capt. Freddy Escobar, president of United Firefighters of Los Angeles City Local 112, said in a statement that the union encourages its members to be vaccinated, but does not support any policies that make vaccine mandates “a condition of employment.”

Most firefighters have “voluntarily been vaccinated and more are choosing to do so each week,” Escobar added.

As of June, a little over half of L.A. firefighters were at least partially vaccinated, according to the Los Angeles Times.

Currently, 54.3% of LAFD sworn personnel are fully vaccinated, according to the LAFD.

The union is working with Los Angeles officials to prevent first responders from leaving their jobs, Escobar said.

“We are in discussions with the City because our highly skilled and experienced LAFD Firefighters and Paramedics cannot be easily replaced – especially in a department that is already understaffed,” Escobar said. “The unexpected departure of even a small percentage of our workforce would have a devastating impact on public safety in Los Angeles.”

Editor’s note: This story initially included an incorrect spelling of the LAFD captain’s first name. It has been corrected.