New York, New York - Influencer Kai Cenat accidentally started a riot when a give-away drew an unexpectedly large crowd in New York's Union Square on Friday which degenerated into violence, leaving people injured and prompting a massive police turnout, authorities said.

It all started with an Instagram post from the 21-year-old YouTuber, calling on fans to meet him in lower Manhattan for a live-streamed event where he would hand out gifts including PlayStation 5 game consoles.

Thousands of people – at least 2,000 according to some reports – gathered very quickly on Union Square and surrounding streets in the hopes of seeing Cenat, who has millions of followers on social media.

As the streets heaved, young men started throwing objects from a nearby construction site, targeting people in the crowd and the police, who were rapidly deployed in large numbers.

Footage and photos showed people surrounding and blocking vehicles, with some kicking and smashing cars.

"People were bleeding from their heads, from their faces ... people were suffering out here," said New York City Police Chief Jeffrey Maddrey at a press briefing

"There were a lot of people, it was uncontrolled... a lot of young people got hurt."

In the end, it took around 1,000 police officers to disperse the impromptu gathering.

Several people were arrested, Maddrey said. Cenat was taken in for questioning, but had not been formally detained.