TAMPA, JAN. 22 -- As the fans and followers of pro football in general and the Super Bowl in particular continued to gather here today, the attention was as focused on protecting the game as playing it.

An NFL source described league officials as "very nervous" about the possibility that the Super Bowl between the New York Giants and the Buffalo Bills could be a terrorist target. However, league and police officials said there had been no specific threats.

To attend the game Sunday, everyone will have to submit to a police search with metal detectors. No still or video cameras, televisions or radios can be carried inside for use in the stands.

Tampa Stadium was sealed off after today's team picture and interview day, and concrete barricades and a six-foot chain-link fence have been erected around it. Reporters entering the stadium today were brushed down with portable metal detectors, and cameras, tape recorders, portable computers and other electronic equipment were searched.

Only four entrances -- two each for pedestrian and vehicular traffic -- remain open and vehicles were being searched before entering and leaving the stadium.

A drug-interdiction helicopter circled the stadium for part of today's events, and players, seeing the beefed-up security and noting the helicopter, reacted nervously.

Since the fighting began last week, security has been tightened everywhere -- from extra measures to protect the Miami city water system to closing the highway over Grand Coulee Dam in Washington state.

But the Super Bowl presents a special array of problems -- with the difficulties of protecting a crowd of 75,000 at a sporting event magnified because the game itself is uniquely American. The possibility of a terrorist attack has been raised at past Super Bowls, and this game remains the kind of American symbol targeted by Iraqi President Saddam Hussein recently on Baghdad radio when he appealed to Muslims to attack "interests, facilities, symbols and figures" of the allied forces.

"The Super Bowl is the quintessential American institution," said Billy Vincent, a former Federal Aviation Administration security specialist who designs security systems for airports and private businesses. "It represents a perfect opportunity for terrorists. It will be viewed all over the world."

"I'm particularly nervous," Giants defensive end Leonard Marshall said. "I'm trying not to be overly concerned. You try to go forward with your preparation and not dwell on the other stuff too much."

Giants linebacker Carl Banks said he has not yet convinced his father to fly from Flint, Mich., to attend the game. "He's still considering it," he said. "I want him to be here, but I'm not going to make him come if he feels uncomfortable about it. I think they'll take all the right measures. What can you do anyway? We've worked too hard to get here and we aren't going home."

U.S. officials say they have received no threats, nor discovered any evidence that the Super Bowl faces imminent attack.

Each year the NFL and the task force serving as host for the game and the weeklong festivities marshal a huge security force. Badges must be worn, tickets are scrutinized and there is a tension about the inevitable questions of "what if." Still, certain precautions are being strengthened this year. Spectators driving to the game may find that police want to search a car's trunk. No spectators will be allowed inside the stadium with umbrellas, and bottles and cans will be confiscated.

"The only thing you can come in with is a blanket," said Tampa Public Safety Administrator Bob Smith, adding that fans should be prepared to have that searched too.

Americans are not accustomed to such checks, in part because terrorist incidents occur infrequently in this country. At an afternoon briefing given by the league to the Super Bowl media contingent, there were snickers when a reporter asked how the police planned to guard against an air attack.

But the image, which calls to mind something as fictional as the movie "Black Sunday" or as real as the terrorist attack at the 1972 Olympics at Munich or the 1988 bombing of Pan Am Flight 103 over Lockerbie, Scotland, is not being ignored. Now that the United States is at war, officials are taking no chances.

Smith said 1,700 law enforcement personnel, from the local county sheriff's department to FBI antiterrorist agents, have been enlisted to protect Tampa Stadium, with 500 scheduled to be on hand for the game. This number does not include private security personnel hired by the league.

Smith acknowledged that, ultimately, there is no way to guard against sophisticated terrorist attack. The effort here is to keep out weapons and crude bombs. But establishing a terrorist network takes time, and officials said they have no evidence such a network exists in this country.

The Pan Am bombing, carried out with less than one pound of plastic explosives concealed in an audio cassette recorder, took months of planning.

"It is not simple, setting something up," Vincent said. "It takes many months and many individuals and many locations. You have to support all those people and get them in place weeks before and get a method of attack in place."

Despite the precautions, game preparations are proceeding as normally as can be expected in a time of war. The players give interviews, and hotels are filling.

Linebacker Gary Reasons said the Giants hadn't discussed the possibility of trouble and added: "No, I'm not worried. I know these people will do a good job. This is a huge event and I'm confident they're going to take care of us."

However, several players admitted they felt uncomfortable celebrating a football game while American servicemen are in the Middle East.

"It's not so much the security arrangements you're concerned about," Giants quarterback Jeff Hostetler said. "It's that we've got guys with people over there. It's a tough time. We're playing a game and they're fighting for their lives. We've got a job just like everyone else and we've got to do the best we can."

"I am nervous, but there's nothing I can do," said Bills linebacker Cornelius Bennett. "I wish the guys {in the armed forces) well and I'm sure they'd want us to go on with our lives. I don't have any problem with my family being here. This may be the only time I play in this game and I'm going to take advantage of it."