Dozens of half-dead people blindly staggered through the streets of a Brooklyn neighborhood known as “Zombieland” Tuesday morning, propping themselves up against fire hydrants and vomiting foam down their shirts.

But the apocalyptic scene wasn’t for a movie. The victims had apparently smoked a bad batch of the “synthetic marijuana” drug known as K2 — and 33 people had to be hospitalized.

“It looked like a scene out of ‘The Walking Dead,’ ” said Brian Arthur, a lifelong Brooklyn resident who posted footage of the disheartening scene on Facebook.

“These guys were wandering around, stumbling all over the place, and were completely out of it,” he told The Post. “They didn’t know their whereabouts, and some couldn’t even get up off the floor. One guy was even trying to hold himself up with a Johnny pump [fire hydrant]. It was ridiculous.”

In Arthur’s video, police can be seen corralling some of the drug users as others lose their minds.

“Look at these dudes — they can’t even stand straight,” he says, while walking through the junkie wasteland, panning to people passed out on the concrete. “This is crazy!”

Cops said the druggies started dropping like flies at around 9:40 a.m., with most of them being found on the sidewalk and subway platforms near Broadway and Myrtle Avenue — a notorious spot for K2 users that has been dubbed “Zombieland” by cops and residents.

“That area is ground zero for K2 addicts,” a police source said. “They have people there who are zonked out on K2 all the time.

“There is a store at the corner there that sells it and there’s a methadone clinic nearby.

“It’s believed that people who go to the methadone clinic are also using K2.”

The victims were taken to Woodhull Medical Center and Wyckoff Heights Medical Center and were all expected to survive, cops said.

“The majority of these people who were doing this were young, teenage guys who hang out in the streets,” Arthur said.

Police on Tuesday said they initially received a call for multiple overdoses outside a building adjacent to Bushwick City Farm, which provides free food, clothing and educational programs.

Officers found eight afflicted individuals upon their arrival, and 14 more later.

“Obviously, it was a bad batch [of K2],” a police source said. “They are lucky they didn’t die.”

A Bushwick City Farm volunteer told The Post that K2 users meet on benches outside the garden.

“We’ve been trying to push people away from the garden area who are smoking this stuff,” said Jason Reis, 34. “They’ll often try to congregate out front. In the last week or so, we’ve put a sign that said: ‘No smoking K2.’ ”

Reis added that residents of Stockton Street and the surrounding area have been contending with K2 users for at least the past three years, noting, “There’s always people passed out on the streets. I saw a guy was puking on the street earlier.”

Arthur recalled how he once saw a K2 user casually taking a stroll with his pants around his ankles.

“It was one of the craziest things I’d ever seen,” he said. “The guy was walking around half-naked. It was insane.”

While residents claimed K2 has been a problem for years, police sources said they had never had an incident as serious as Tuesday’s.

“[Thirty-three people] is a tremendous amount in one morning,” a source said. “That is a busy week.”

Police sources and residents in the area told The Post that the K2 is being purchased from a deli at the corner of Myrtle and Broadway. The store, Big Boy Deli, has been raided by police several times in the past, most recently last Thursday, they said.

“The sheriff’s department came in and closed it down for a couple days, but then it was open again,” Arthur recalled. “By Monday, they were right back to selling.”

Last year the popularity of the chemical-laced drug skyrocketed among young pot smokers and the city’s homeless population because of its low price, around $5 a pop.

In October 2015, Mayor Bill de Blasio signed into law three measures that made possession of the drug with intent to sell a misdemeanor, punishable by up to a year in jail and a $5,000 fine.

Still, sources said there is nothing cops can do about people who smoke it.

“There cannot be any arrests made of people possessing K2,” a police source said.

Additional reporting by Jamie Schram

Everything you need to know about synthetic marijuana, aka Spice: