Police called to Bedford-Stuyvesant neighbourhood of Brooklyn after reports of victims lying on the sidewalk shaking

At least 33 people were hospitalized on Tuesday from an apparent mass drug overdose of synthetic marijuana, in an area of New York City where the drug is said to be used at “epidemic” levels.

Spice: Americans turn to dangerous 'synthetic marijuana' to evade drug tests Read more

Authorities said they began receiving calls at around 9.30am of people collapsing near an intersection in Brooklyn that the news website DNAinfo said was known as the “epicenter” for synthetic marijuana – or K2 – use.

Brooklyn resident Brian Arthur broadcast live on Facebook from the scene, saying it looked like “zombieland” as he panned to images of incapacitated and agitated people being attended to by emergency responders. “I just came home from work and I’m seeing this, like, what the hell?” Arthur said. “Every freaking step they laid out.”

One man who was barely able to stand up wandered into the street as emergency medical staff attempted to help him. Close by, another man was frozen like a statue until he started falling slowly forward, only upright because he was leaning into a fire hydrant.

Erowid Center (@Erowid) Mass #K2 Overdose in New York Leaves Users Collapsed & Vomiting. At least 33 hospitalized. https://t.co/59LcdwvEew pic.twitter.com/ZhjEMxxqFZ

Other witnesses described people falling to the ground, lying crumpled on the pavement and immobilized against walls and poles. “I saw two people smoking for maybe 15 minutes. Then they fell to the floor,” Rafael Perez, who works in the neighborhood, told DNAinfo.

The city health department said it was investigating and monitoring emergency rooms across the city.

“We remind New Yorkers that K2 is extremely dangerous,” the agency said in a statement. “The city’s public awareness efforts and aggressive enforcement actions over the past year have contributed to a significant decline in of ER visits related to K2.”

Calls to poison control centers about synthetic cannabinoid exposure. Calls to poison control centers about synthetic cannabinoid exposure.

The mayor’s office announced in May that there had been an 85% decline in emergency room visits tied to the drug since July 2015. In that period, the city seized more than 10,000 packets of K2, sold under names like Spice, Mr Bad Guy and Red Giant.

There have been more than 6,000 synthetic cannabinoid-related emergency room visits in 2015 and at least two confirmed deaths related to the drug, according to New York’s health department.

The agency said those visits were mostly by males, with a median age of 37, who “are disproportionately residents of shelters and individuals with a psychiatric illness”.

Because the chemical mixture of K2 changes packet by packet, it has an unpredictable impact on consumers. Some of the known health effects of K2 include extreme anxiety, vomiting, seizures, hallucinations, reduced blood supply to the heart and kidney failure.

It is illegal to possess, sell or manufacture the drug in New York City, but high use of the drug has been reported on the border of Brooklyn’s Bedford-Stuyvesant and Bushwick neighborhoods around the intersection of Myrtle Avenue and Broadway, where some residents have posted hand-painted signs that say “no smoking K2”.

The NYPD has been conducting raids on shops suspected of selling K2 as part of a citywide crackdown on the drug. Authorities also canvassed homeless shelters and drug treatment clinics to warn about the reactions to this batch of K2 on Tuesday.