A device ignited outside Gracie Mansion during a clash between opposing protest groups Saturday was an improvised explosive capable of causing “serious injury or death,” the NYPD said Sunday.

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.

The Gracie Mansion counterprotesters accused of throwing homemade bombs came to New York with a powerful powder explosive nicknamed “Mother of Satan,” a notebook filled with handwritten notes — and a plan to go “bigger” than the 2013 Boston Marathon bombing,

The NYPD said the device thrown outside Mayor Zohran Mamdani's residence was an "improvised explosive device" capable of causing serious harm.

The NYPD is investigating three homemade explosive devices found near Gracie Mansion as "an act of ISIS-inspired terrorism."

There were protests on Saturday when two individuals ignited several explosive devices.