New York, New York - A homemade incendiary thrown near anti-Islam protesters outside New York Mayor Zohran Mamdani's residence was a viable improvised explosive device "that could have caused serious injury or death," police said Sunday.

Two suspicious devices were thrown by a man identified by police as Emir Balat near the protest Saturday, which was led by a far-right influencer to oppose public Muslim prayer.

An AFP correspondent at the scene heard Balat shout "Allahu akbar" ("God is the greatest") during the incident, which is under investigation by counter-terrorism detectives.

"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 smoke bomb. It is, in fact, an improvised explosive device (IED)," the NYPD said in a statement Sunday.

Police had said Saturday that the devices were jars wrapped in tape and containing nuts, bolts, and screws – typical components of an IED.

Two men were arrested after Saturday's incident: Balat and Ibrahim Kayumi, who reportedly handed over a device that was thrown by Balat, who dropped it near a line of police.

The events unfolded after the far-right influencer Jake Lang staged a demonstration outside Gracie Mansion, the official residence of Mamdani, who is Muslim.

Lang was protesting alleged "Islamification" and calling for an end to "public Muslim prayer" in New York.

His protest drew around 20 people, while a counter-protest drew about 125. Police Commissioner Jessica Tisch said Saturday she did not believe Mamdani was home at the time.

On Sunday, the police bomb squad used a robot to inspect a car near the scene of the previous day's incident, an AFP correspondent saw.

A police spokesman could not confirm if the deployment was linked to the events of Saturday.