Is the Joker running loose in New Jersey? Social media seems to think so.

A major motion picture starring two A-list celebrities could be being filmed in Belleville. Pictures and videos on social media show what looks like the "Joker 2" filming in Belleville at the old Essex County Isolation Hospital.

News 12 New Jersey's Lauren Due visited the set location Monday morning where trailers, tents, old fashion Gotham labeled police vehicles, mock news vans, and production lights are spotted in the area. The Essex County Hospital is still seen engraved on top. Police and security are surrounding the area. 

Many fans believe the movie set is for “Joker: Folie a Deux," which means "Madness for Two" in French.

Joaquin Phoenix is playing the Joker and Lady Gaga is set to play Harley Quinn. Phoenix was spotted in New York City on Sunday.

"This is the first time I’ve seen around here. There’s a film. This building has been here a long time, it’s not active. They fixed it and last night I asked my self what’s going on?," said Linda Cortez, a Belleville resident.

Belleville Mayor Michael Melham says he cannot say which movie is being filmed in the area but posted production photos.

“Joker: Folie à Deux” is expected to be released in theaters in Oct. 4, 2024.