"Certainly, we're keeping an eye on activities around the world, but as of this time, there are no threats directed against this event that we're aware of," New York City Police Commissioner William Bratton said a security briefing in Manhattan.
Because this year's Super Bowl has the distinction of relying on mass transit to take up to 30,000 fans to the game, the deadly bombings in the southern Russian city of Volograd have raised worries here, said Col. Rick Fuentes, head of the New Jersey State Police. The suicide attacks on a trolleybus and a train station that killed more than 30 people within weeks of the Winter Olympics also prompted a series of meetings among the planners for Super Bowl security, he said.
Local officials are counting on the FBI and the Department of Homeland Security "to keep an eye on and brief us on those events," Fuentes said. "There is a concern with mass transit and we've prepared ourselves for it."
Trains, buses and cars taking fans from New York and parts of New Jersey to the stadium and back again "are going to be scanned, they're going to be checked, they're going to be swept," he said.
In Manhattan, the NYPD is drawing on its experience securing the annual New Year's Eve celebration in Times Square, the New York City Marathon, the U.N. General Assembly and other high-profile events to secure "Super Bowl Boulevard," a 13-block street fair on Broadway.
The department has deployed hundreds of extra uniformed and plainclothes police officers to the area. It's also relying on bomb-sniffing dogs, portable radiation detectors and a vast network of surveillance cameras to detect trouble.
In the weeks leading up to the Super Bowl, the NYPD rehearsed its response to a variety of potential threats, including "the backpack left unsecured scenario," Bratton said. "We are very, very well-prepared."
The state police plan to assign up to 700 troopers at the stadium on Sunday, Fuentes said. A security centre has been set up in a hollowed-out building across a highway from the stadium that's slated to become a mammoth retail and entertainment complex.
A 24-hour FBI command centre will monitor the latest counterterrorism intelligence, said Aaron Ford, head of the FBI's Newark office. Measures have been taken to protect power grids and to make sure there's plenty of backup energy in case of another blackout like the one last year at the game in New Orleans, said Jeffrey Miller, the NFL's head of security.
"This year we're going to try to go blackout free," Miller said. "One thing that I've learned is that you don't want to be overconfident. You want to prepare and be ready. You just don't know what you might face on game day."
Randy Killikevc, a tourist from Tennessee who attended a Super Bowl party in Byrant Park on Wednesday, said possible threats against the Super Bowl weren't on his mind.
"If terrorists were going to strike New York why not do it on New Year's Eve? There's lots more people here (then)," he said.
Associated Press writers Karen Matthews and Dave Porter contributed to this report.