New Year's Eve revelers pack NYC's Times Square under tight security

More than a million people were expected to crowd into New York City's Times Square under heavy security on Thursday to celebrate the arrival of 2016 with the traditional dropping of the New Year's Eve crystal ball.

Throngs of people began streaming into the area early in the day, preparing to spend hours outdoors before the official festivities begin with the lighting of the ball at 6 p.m. EST (2300).

With memories of the deadly attacks in Paris and California still fresh, police took extraordinary measures to ensure security at an event that has come to define the New York experience for many visitors to the largest U.S. city.

"This is the center of the world on New Year's Eve," said Rick Milley, 60, who traveled from Boston with his wife, Debbie, 59, to ring in the new year in Times Square.

"This was on our bucket list," Debbie Milley said as the couple took pictures of themselves using a selfie stick.

The pair have spent the holiday in New York before but never in Times Square, the Midtown Manhattan crossroads that is a year-round tourist draw, filled with chain stores, family restaurants and flashy advertising displays.

About 6,000 uniformed and undercover police officers, 500 more than last year, were expected to be in the area on New Year's Eve, with the help of mounted patrols, bomb-sniffing dogs, radiation detectors and other sophisticated technology.

"We have the capacity here to take a celebration like this and to make sure it's exceedingly safe," New York Mayor Bill de Blasio said in an interview with CNN. "You'll see lots of police officers in regular uniforms and regular weaponry but you'll also see the heavily armed officers."

The famous New Year's Eve ball, which is 12 feet (3.66 meters) in diameter and weighs nearly 6 tons, descends on a pole mounted on top of One Times Square, a narrow wedge of a building at the southern end of the square. The descent starts at exactly 11:59 p.m. EST (0459 GMT).

"I always wanted to come here, but never took the chance," said James Gomez, 39, of New Haven, Connecticut, as he surveyed the area with a group of friends looking for a prime viewing spot.

Gomez came to Times Square even though he said he was concerned about the area being targeted in an attack.

"I'm scared," he admitted.

In the hours before midnight, revelers like Gomez and his friends can listen to musicians such as Carrie Underwood and Jessie J performing on multiple stages set up in the area.

In addition, more than 100 million Americans and 1 billion people worldwide were expected to watch the festivities on television.

The city for the first time will use its new Critical Response Command counterterrorism unit, which includes more heavily armed officers, to patrol Times Square.

The unit is trained to detect and respond to planned attacks such those in Paris that killed 130 people on Nov. 13, or the rampage in San Bernardino, California, in which 14 were slain.

Before entering Times Square, visitors will have to pass through tight security checkpoints. Police will stop visitors from carrying backpacks and large bags into the area, and will search smaller bags and scan people with metal detectors.

Once inside the square, spectators were to be funneled into one of the dozens of viewing pens where law enforcement officers can closely monitor and control the crowd. After entering the pens, visitors cannot leave and re-enter.