Thirty-three people were hospitalized from an apparent synthetic marijuana overdose Tuesday morning after they were discovered in and around a Bedford-Stuyvesant building, police said.

Authorities received a 911 call about men smoking marijuana at 362 Stockton St. around 9:38 a.m. and found “multiple [people] with an altered mental state,” according to an FDNY spokesman.

“It was like ‘The Walking Dead.’ A zombie scene,” said Brian Arthur, 38.

Nury Rodriguez, 55, who works at a barbershop on Stockton Street said she saw several people fall a couple of minutes after they were smoking.

“It was the first time I saw something like that. I was scared,” she said.

The patients were transported to Wykcoff and Woodhull hospitals in serious condition however their identities weren’t immediately released. A source said that the ages of the victims vary and some were as old as 52.

Pedestrians posted images and videos to social media accounts showing the victims slumped on the ground and appearing dazed as paramedics led them into ambulances.

“They were out cold,” said Juan Gonzalez, 57. “They were all spread out.”

Both the FDNY and NYPD said the investigation was ongoing.

Residents said synthetic marijuana, or K2, is a big problem in the neighborhood and it’s been getting worse. Jason Reis, 34, who manages the Bushwick City Farm on Stockton Street, had to put up signs that read “No Smoking K2,” because so many people were smoking it in front of the lot.

“The difference this year, compared to other years, is it’s always new people,” he said. “It used to be the same five or 10 people.”