"We have to interview both sides," said New York City Police Commissioner Dermot Shea about the disturbing incident.

Everyone showing up for the confetti-filled festivities should expect to be wanded with metal detectors before being ushered to one of 65 viewing pens set up around Times Square to prevent overcrowding.

Reports on social media suggest that people rushed into buildings and stores after an explosion-like sound.

Their latest daredevil stunt was streamed live on ABC and watched by thousands of spectators from below.

Flames started to shoot out of the LED billboard just after 3 p.m. Saturday.

The nearly 6-ton (6-metric ton) ball was raised Sunday to the top of a 130-foot (40-metre) pole at One Times Square.

The drone will give "visual aid and the flexibility of being able to move a camera to a certain spot with great rapidity through a tremendous crowd,” said Deputy Commissioner of Intelligence and Counterterrorism John Miller.

The real Times Square ball drop crowd likely has fewer than 100,000 people, crowd science professor G. Keith Still said.

“While the undercover’s violent and encouraging comments to Mr. El Bahnasawy no doubt advanced law-enforcement objectives, they also contributed to Mr. El Bahnasawy’s radicalization,” defence lawyers said.

The strange incident prompted police to shut down part of the busy area and call a beekeeper as tourists looked on.