NEW YORK – The distant whir of helicopter blades seems ever-present in Times Square this week, audible above the regular din of honking horns and music.

That’s because high above the neon signs and theater billboards, a police chopper continuously circles the area deploying thermal imaging sensors to detect any bombs or other serious weapons on the ground. After last year’s Boston Marathon bombing and recent terrorist threats in Russia ahead of the Winter Olympics in Sochi, security officials here are extending Super Bowl security well beyond MetLife Stadium in New Jersey.

“As of this time, there are no threats directed against this event that we’re aware of,’’ New York police commissioner Bill Bratton told reporters Wednesday. “At the same time, the benefits of hosting this event here in this region is ... the NYPD and its colleagues in the area have some of the best counterterrorism capabilities in the world. Not only in detection, but response.’’

There are 100 law-enforcement agencies from New York, New Jersey and the federal government working to keep fans and players safe as Super Bowl week plays out.

Representatives of several top agencies, including the Department of Homeland Security, FBI, NYPD and New Jersey State Police held a joint news conference Wednesday to spell out details of one of the biggest security operations ever undertaken for a sports event in this country.

New Jersey police superintendent Rick Fuentes said the stadium and surrounding areas are effectively “locked down” by a 2.5-mile long fence through which all vehicles are being subjected to thermal scanning before entering the security zone. A “public-safety compound’’ has been set up on site with 120 workstations where policing agencies can monitor and assess any threats that surface during and around Sunday’s game.

There will be 700 uniformed New Jersey State Police officers at the game, Fuentes said, and hundreds positioned on rail platforms and stations and at bus stations.

Officials expect that between 12,000 and 15,000 fans will arrive at the stadium by light rail and up to 15,000 more by bus. There are only 11,000 parking spots available for use — only 40 percent of normal capacity — and all have already been reserved by fans ahead of time.

“This is a mass transit Super Bowl,’’ Fuentes said.

Jeff Miller, NFL vice president and chief security officer, said he hopes the screening process for fans entering the stadium won’t take longer than 15 to 20 minutes once inside the security perimeter. The NFL is reminding fans they can only bring in:

• Bags that are clear plastic, vinyl or PVC and 12 by 6 by 12 inches.

• One-gallon clear plastic freezer bags.

• Small clutch bags of 4.5 by 6.5 inches with or without a handle or strap. These can be brought in along with one of the clear plastic bag options.

Prohibited items include outside food and beverages, camcorders, pets, beach balls, footballs, umbrellas and noisemakers. Only small cameras — with lenses not exceeding six inches in length — will be permitted, along with binoculars, but no carrying cases for either are allowed inside.

Across the Hudson River in New York, the NYPD is coordinating security measures to ensure areas with heavy Super Bowl activities this week — like Times Square and Midtown — are kept safe. Be it the helicopters above or added police presence on the streets, the idea is that threats might not necessarily come during the game itself.

Fans are asked to do their part, by arriving at the game early and respecting the rules about what to bring in. Homeland Security Secretary Jeh Johnson added that fans both at the game and around the city can help most by staying alert.

“If you see something, say something,’’ he said.

Geoff Baker: 206-464-8286 or gbaker@seattletimes.com.

On Twitter @gbakermariners