A device thrown by a counterprotester at an anti-Islam demonstration in New York City on Saturday was confirmed to be an improvised explosive, according to a preliminary police analysis.

Two people were in custody for their alleged role in the confrontation, which unfolded during a “Stop the Islamic Takeover of New York City” event led by the far right activist Jake Lang outside the Manhattan residence of Mayor Zohran Mamdani.

The sparsely attended event drew a far larger group of counterdemonstrators, including one person who tossed a smoking object containing nuts, bolts, screws and a “hobby fuse” into the crowd, police said.

In a social media post Sunday, Police Commissioner Jessica Tisch said the department’s bomb squad determined the object wasn’t a hoax device or smoke bomb, but an “improvised explosive device that could have caused serious injury or death.”

The device extinguished itself steps from police officers, Tisch noted. The same person who threw it then received a second device from another counterprotester, which was dropped and did not appear to ignite, the commissioner said.

Charges against the two counterprotesters were still pending. Tisch said police were working with federal prosecutors and the FBI on the case.

“Violence at a protest is never acceptable,” Mamdani said in a statement Sunday. “The attempt to use an explosive device and hurt others is not only criminal, it is reprehensible and the antithesis of who we are.”

A person associated with Lang’s protest was also arrested and charged with reckless endangerment, assault and unlawful possession of a noxious matter after allegedly macing counterprotesters, police said.

Lang was previously charged with assaulting an officer with a baseball bat, civil disorder and other crimes before receiving clemency as part of President Donald Trump’s sweeping act of clemency for Jan. 6 defendants last year. He recently announced that he is running for U.S. Senate in Florida.

Earlier this year, Lang organized a rally in Minneapolis in support of Trump's immigration crackdown, drawing an angry crowd of counterprotesters that quickly chased him away.