When Henry Towbin first learned on Thursday afternoon that there might be extra vaccine doses at the Brooklyn Army Terminal, the 29-year-old grad student wasted no time. Within minutes, he'd rallied his wife and parents into an Uber, which drove them from Park Slope to the new city-run vaccine site in Sunset Park.

There, he said, healthcare workers directed them to a specific "walk-in line," which was roughly 70 people long at the time. His skepticism about the secondhand tip — it'd come from a school nurse, who'd heard it from an Army Terminal employee — soon disappeared.

"They were very slowly pulling from the walk-in line," he told Gothamist. "I was like, if these are all going to go to waste and this is my opportunity, I’ll do it."

As the news of the excess doses spread on social media, hundreds of New Yorkers descended on the site, fueling traffic jams that spanned for blocks and a near-stampede. Police were called to the scene to disperse the crowd, which witnesses pegged at close to 500 people, including some who'd driven all the way from Long Island.

"It just kept getting longer and longer," said Towbin. "It was like a bread line."

Shortly after 5 p.m., Bill Neidhardt, the mayor's press secretary, attempted to debunk the "misinformation" on Twitter, urging people to steer clear of the site if they didn't have an appointment. City Councilmembers described the rumors as "bogus" and "inaccurate."

For many New Yorkers, the apparent hoax recalled the early days of the pandemic, when false text chains about the city being placed under martial law ricocheted across the internet.

But those who actually arrived at the Brooklyn Army Terminal on Thursday said the reality was more complicated. Despite the city's claims that the message was untrue, there were extra doses being administered on a first-come, first-serve basis. The real trouble was that too many people showed up.

In one video, an employee can be heard telling the crowd that "today was an exception. We wanted to offer it. It was a single event. Unfortunately, we're not able to offer walk-ins anymore." In another, a different healthcare worker explains: "There were extra vaccine, but we don't have the manpower."

"I heard what the woman said with my own ears,'" said Ty Henry, a 45-year-old Bay Ridge resident who rushed to the Army Terminal after seeing the news online. Though she ultimately left without a vaccine, she said she was most annoyed at City Hall's depiction of the incident as a problem of misinformation. "If you made a mistake, just say we made a mistake. But stop calling other people liars. It wasn't a hoax."

On Friday, a city official acknowledged to Gothamist that there were a significant number of vaccine doses at Brooklyn Army Terminal that were set to expire on Thursday night. Some of those doses were provided to other hospitals, while staffers planned "to get rid of" the others, according to the source, who spoke on the condition of anonymity.

"Clearly someone with that knowledge took that and blasted it out," the person added. "That's not how we want to do things."

It's not unusual for some vaccination sites to have a few extra doses at the end of the day. Under state regulations, those shots can be administered to people not otherwise eligible for the vaccine. But the number of leftovers at the Army Terminal was more significant, the official said, raising questions about why one site had so many doses that had not been used.

"There’s a real and valid concern out there that vaccines are going to waste, yet we are sending people to a website that is constantly insisting all appointments are booked," said Councilman Justin Brannan, who represents the neighborhood. "The city must clearly communicate what the official protocol is for 'extra' doses, and make this process easier to navigate, before people take to WhatsApp to solve the problem themselves.”

It's still unclear how many doses were provided to those without appointments, and whether any were thrown out on Thursday.

At a time when so many are desperate for immunization, the debacle illustrates the ongoing operational challenges the city and state are facing as they rush to get shots into the arms of New Yorkers, amid continued questions about the federal supply. Mayor de Blasio has warned that the city will run out of vaccine doses next week, and both Mount Sinai and NYU Langone have stopped booking new appointments and canceled existing ones.

After leaving the site without a vaccine on Thursday evening, Towbin, the 29-year-old grad student, said he empathized with the hurdles of mass vaccine distribution, but still felt as though the city's efforts were falling short.

"It’s a hard thing for any administrator to deal with. I get it," he said. "But they had months to plan for this. It’s definitely been haphazard."