The New York City police union warned the public about a rowdy demonstration promised by antifa against the city’s public transportation police.

In a video posted online, three masked antifa members alerted their followers of a protest planned for Jan. 31. The three men asked followers to gather in the subway to protest its law enforcement and its ticket prices.

“We encourage you to link up with your friends, your family, and think of the ways you can move in affinity to build and f--- shit up on J31 [Jan. 31] all day long,” the masked leader said. He later added, “The mood for J31 is simple: F--- your $2.75, no cops in the MTA, free transit, no harassment, period, and full accessibility.”

In a tweet posted Friday morning, the police union warned the public of the planned protest, writing, “New Yorkers should pay close attention: this is true endgame of the anti-police movement, an end of all policing & destruction of public order. Our members have spent their careers — and in some cases given their lives — to bring public safety back to NYC. We can't go backwards.”

New Yorkers should pay close attention: this is true endgame of the anti-police movement, an end of all policing & destruction of public order. Our members have spent their careers -- and in some cases given their lives -- to bring public safety back to NYC. We can't go backwards pic.twitter.com/X72vVioCVi — NYC PBA (@NYCPBA) January 30, 2020

A representative for the New York City Police Department told Fox News that the department “is aware of the demonstration and will have an adequate police presence in place.”

Antifa, which claims to be anti-fascist, is an often-violent activist group whose masked supporters protest law enforcement and work to promote left-wing policies. Antifa was declared a terrorist organization by the New Jersey Homeland Security office in 2017. While many disavow antifa’s methods, some prominent Democrats support the group.