Incident took place during anti-Islam protest by rightwing agitators outside Gracie Mansion, where the New York City mayor lives

The throwing of two improvised explosive devices – allegedly by counter-protesters during an anti-Islam demonstration – outside the residence of New York mayor Zohran Mamdani on Saturday was an act of “terrorism” inspired by the Islamic State terror group, officials said Monday.

Jessica Tisch, the New York police department (NYPD) commissioner, told reporters at a press conference in Manhattan that two men from Pennsylvania were arrested at the scene – and that a federal criminal complaint against them would be filed later on Monday.

The incident took place on Saturday during an anti-Islam protest by rightwing agitators outside Gracie Mansion on Manhattan’s upper east side, when Mamdani, the city’s first Muslim mayor, and his family were not at home.

The devices, which Tisch said contained triacetone triperoxide (TATP), a homemade and highly volatile chemical explosive known as “mother of Satan”, were allegedly thrown by counterprotesters she named as Ibrahim Kayumi, 19, and Emir Balat, 18.