Six New York City firefighters upset with an impending COVID-19 vaccine mandate for city workers were relieved of duty Friday and face suspension after driving a firetruck to a state senator’s office and threatening his staff over the requirement, which the state lawmaker had nothing to do with.

The angry display came as the Big Apple braced for the possibility of closed firehouses, fewer police and ambulances and mounting trash come Monday as thousands of municipal workers remain unwilling to get the shots.

Police officers, firefighters, garbage collectors and most other city workers faced a 5 p.m. Friday deadline to show proof they’ve gotten at least one dose of the COVID-19 vaccine.

Workers who don’t comply will be put on unpaid leave starting Monday. Nearly one-fifth of city employees covered by the impending mandate have yet to receive at least one vaccine dose as of Thursday.

Fire Commissioner Daniel Nigro swiftly condemned the incident, in which members of Ladder 113 drove a firetruck to state Sen. Zellnor Myrie's office and reportedly told his staff they'd have “blood on their hands” because of staffing shortages resulting from the mandate. 

“This is a highly inappropriate act by on duty members of this Department who should only be concerned with responding to emergencies and helping New Yorkers and not harassing an elected official and his staff," Nigro said." The members in question have been immediately relieved of duty and will face disciplinary action.”

Messages seeking comment were left with Myrie's office and the firefighters' union. 

Friday’s incident was a dramatic escalation between the city's unvaccinated rank-and-file and Mayor Bill de Blasio's administration, which has held firm on the deadline amid protests and a legal challenge.

Hundreds of firefighters rallied Thursday outside the mayor's official residence, sanitation workers appeared to be skipping garbage pick ups in protest and the city’s largest police union went to an appeals court seeking a halt to the vaccine requirement. 

Pat Lynch, president of the Police Benevolent Association, said the hard deadline “sets the city up for a real crisis.” Andrew Ansbro, president of the Uniformed Firefighters Association, warned longer response times will “be a death sentence to some people.”

De Blasio said Thursday that the city has contingencies to maintain adequate staffing and public safety, including mandatory overtime and extra shifts - tools that he said were typically used “in times of challenging crisis.”

The mayor called the sanitation slowdowns “unacceptable” and said the department will move to 12-hour and begin working Sunday shifts to ensure trash doesn't pile up.

“My job is to keep people safe - my employees, and 8.8 million people,” de Blasio said at a virtual news briefing. “And until we defeat COVID, people are not safe. If we don’t stop COVID, New Yorkers will die.”

People who refuse to get vaccinated are now a big factor in the continued spread of the virus. Backers of mandates say New Yorkers have a right not to be infected by public servants unwilling to get the shots.

Of police personnel, 16% have not gotten at least one dose of a vaccine, while 29% of firefighters and EMS workers and 33% of sanitation workers have not yet gotten a shot, according to city data. City jail guards have another month to comply. 

As of 8 p.m. Thursday, 33,400 city workers remained unvaccinated.

The fire department said it was prepared to close up to 20% of its fire companies and have 20% fewer ambulances in service while changing schedules, canceling vacations and turning to outside EMS providers to make up for expected staffing shortages.

Police Commissioner Dermot Shea said his department was sending reminders to unvaccinated workers and that NYPD vaccination sites will remain open all weekend. Shea said thousands of officers who’ve applied for medical and religious exemptions will be allowed to work while their cases are reviewed.

More than 700 officers were vaccinated on Thursday alone, the NYPD said, rushing to meet the deadline for the mandate and an extra incentive: workers who get a shot by Friday will get $500.

“On Monday, when this thing really starts being enforced, we're going to check the vaccination status and if you're not vaccinated, no pay and you're going to be not able to work,” Shea said in a video message Wednesday to officers. “I don't think anyone wants that to happen."

Fire department officials are holding virtual meetings with staff, imploring them to get vaccinated.

A Staten Island judge on Wednesday refused a police union's request for a temporary block on the mandate, but she ordered city officials into her courtroom next month to explain why the requirement shouldn't be reversed. If the mandate is deemed illegal, workers put on leave will be given back pay, the city said.

Firefighter Jackie-Michelle Martinez said at Thursday's protest that the ability to choose was “our God-given right” as she questioned the city's decision to move away from its previous policy, which allowed workers to stay on the job if they had a negative COVID-19 test.

“If the weekly testing is working, why are you, Mayor de Blasio, eliminating it?” she asked.

COVID-19 is the leading cause of death of law enforcement officers in the U.S., killing 498 officers since the start of 2020 compared to 102 gun deaths, according to the Officer Down Memorial Page, which tracks police fatalities.

De Blasio on Thursday credited the impending deadline for moving the needle on vaccinations across city government. In the last week, the number of affected workers who've gotten at least one dose rose from 71% to 79%. 

When the state required all workers at hospitals and nursing homes to get vaccinated, a last-minute rush of people to comply meant that a few facilities experienced staffing challenges.

“We expected that a lot of the vaccinations would happen toward the end of the deadline,” de Blasio said. “We also know a lot of people make the decision once they really realize that they’re not going to get paid. That’s just the human reality.”