New York City officials have confirmed that a device ignited and thrown during protests near Gracie Mansion on Saturday was an improvised explosive device (IED) capable of causing “serious injury or death.”

In a statement posted to X on Sunday, NYPD Commissioner Jessica Tisch said the department’s Bomb Squad determined the device was neither a hoax nor a smoke bomb.

“The NYPD Bomb Squad has conducted a preliminary analysis of a device that was ignited and deployed at a protest yesterday and has determined that it is not a hoax device or a smoke bomb,” Tisch wrote. “It is, in fact, an improvised explosive device that could have caused serious injury or death.”

Authorities are continuing to analyze a second device recovered at the scene.

Police arrested Emir Balat and Ibrahim Kayumi at the scene. Both remain in custody.

Three federal law enforcement sources told Fox News that the two suspects are believed to be U.S. citizens.

The NYPD is working alongside the U.S. Attorney’s Office for the Southern District of New York and the FBI through the Joint Terrorism Task Force.

“I want to again thank the brave members of the NYPD who ran towards the danger without hesitation and quickly apprehended the suspects,” Tisch added.

The incident unfolded during dueling demonstrations Saturday morning near East End Avenue and East 87th Street, just steps from Gracie Mansion, the official residence of New York City Mayor Zohran Mamdani.

One rally was organized by right-wing activist Jake Lang to oppose public Muslim prayer. Counter-protesters also gathered at the scene. 

Though police initially kept the groups separated, tensions escalated after pepper spray was deployed during a confrontation.

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Approximately 30 minutes later, authorities say an 18-year-old counter-protester ignited and threw a device toward the protest area. Witnesses reported seeing flames and smoke before it extinguished itself near responding officers.

Police say the 18-year-old then retrieved a second device from a 19-year-old, lit it, and attempted to flee. 

Both suspects – identified as Balat and Kayumi – were taken into custody.

Three additional arrests were made on charges including disorderly conduct and obstructing traffic.

Bomb squad technicians on Saturday described the devices as jars wrapped in black tape, slightly smaller than a football. 

X-rays revealed nuts, bolts and screws inside – materials commonly used as improvised shrapnel – along with a hobby fuse that could be lit. 

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Mayor Zohran Mamdani condemned both the protest and the violence in a statement posted Sunday.

“Such hate has no place in New York City. It is an affront to our city’s values and the unity that defines who we are,” Mamdani wrote. “What followed was even more disturbing. Violence at a protest is never acceptable. The attempt to use an explosive device and hurt others is not only criminal, it is reprehensible and the antithesis of who we are.”

He thanked NYPD officers for their response and said his administration is “closely monitoring the situation.”

The NYPD could not be immediately reached by Fox News Digital for comment.

Fox News’ Bill Melugin and Fox News Digital’s Alexandra Koch contributed to this report.

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