Fireworks explode past the Times Square Ball (rear) after it dropped to signal the start of the New Year in the Manhattan borough of New York January 1, 2016.  [Photo/Agencies]

NEW YORK -- As the glittering crystal ball dropped with live music and the countdown resonating across Times Square, nearly one million delirious revelers burst into cheers, ringing in the new year amid tight security on Thursday.

With memories of the deadly attacks in Paris and San Bernardino, California still raw, the New York Police Department (NYPD) this year deployed nearly 6,000 policemen to safeguard what it called "the biggest and safest New Year's Eve party".

Multi-layered checkpoints are also set up in and around Times Square, manned by policemen with long guns, radiation detectors and bomb-sniffing dogs.

Meanwhile, a special counter-terrorism unit and plainclothes officers were also scattered among the crowds.

"I feel very safe now," said Zachary Freeman, who came from Arizona. "The NYPD is out there, full in force. Every government agency in New York seems to have a presence here, keeping everybody safe, protecting everybody, and doing an outstanding job. So no concerns, everybody out here is just having a great time."

When asked whether he had any hesitation when deciding whether to attend the countdown, Freeman said that it was a spontaneous decision to attend the event, leaving for New York just two hours after making the call at home. "So no hesitation whatsoever," he said.

Paola Duran, a visitor from Algeria, said: "I think we are very secure in America right now, especially tonight, especially after what happened across the world. I feel very secure."