Thousands of people overran New York's Union Square and the surrounding streets on Friday (Aug 4) after a popular live streamer announced a "giveaway" event that grew chaotic, prompting hundreds of police officers to respond and disperse the crowd.

The event was promoted by Kai Cenat, best known for his live streams on the gaming site Twitch and YouTube videos. He had earlier announced a "huge giveaway" on his Instagram account for 4pm local time.

Before the event began, footage from news choppers showed people flinging bottles and chairs, climbing onto the roof of a subway entrance, tearing down construction barriers, standing on top of cars and unloading a fire extinguisher.

Video from TV news helicopters showed Cenat in a black SUV, standing with his head through the moon roof, as people mobbed the vehicle. At least one person fell off the car as it drove away from the scene.

It was not immediately clear what had sparked the chaos.

By 5pm, police had set up barricades around the square and largely contained the crowd.

A spokesperson for the city police department said no injuries had been reported as of 4.45pm and that there was no information yet on the number of arrests.

In a social media advisory, the department urged people to avoid the park, which is near New York University.

Cenat, 21, has 6.5 million followers on Twitch and 4 million subscribers on YouTube. He was named Streamer of the Year in 2022 at the Streamy Awards.