The teen was seen holding up his right index finger -- a universal salute for the terror group -- and grinning at press while being led by a cop and an FBI agent.

New York City police said an explosive device was deployed during a violent clash outside Gracie Mansion, Zorhan Mamdani's residence, on Saturday.

Two teens accused of trying to ignite homemade explosive devices at a protest outside Gracie Mansion over the weekend expressed support for ISIS after their arrest, according to a criminal complaint released Monday.

A device deployed during dueling demonstrations outside Grace Mansion in New York City on Saturday has been found to be an improvised explosive device, according to the NYPD.

Six people are in custody after two homemade explosive devices were tossed outside Gracie Mansion Saturday during competing anti- and pro-Muslim protests, causing a panic. Dozens of demonstrators and counter-protesters fled as smoke started to billow from a device which appeared to have a lit fuse and was wrapped in duct tape.

A device found outside of Gracie Mansion on Saturday during dueling protests in New York City was confirmed to be an improvised explosive device, according to police