While no one was injured in the robbery, the crime highlighted how the Port Authority has to juggle security concerns with the need to accommodate the needs of the 100,000 people who use the complex on an average day. Officials said yesterday that the 10 million-square-foot complex remained one of the safest buildings in the country, and added that the robbery would not result in any Draconian measures to heighten security.

''After an incident like this, you certainly evaluate the measures you have in place,'' said Mark O. Hatfield Jr., a spokesman for the Port Authority. ''But there are a number of issues to deal with here. This is not a Federal nuclear laboratory, which you can completely shut down to public access. Within an environment like this you have to provide access and egress for a large number of people.''

''I think that our track record over the past 26 years has certainly been an excellent one,'' he added. ''And, while no one will be satisfied until it's perfect, I think it is safe to say that this is the most secure office building in Manhattan.''

According to the Port Authority police, the three robbers, all carrying duffel bags, entered One World Trade Center, the north tower, about 8 A.M. They took a passenger elevator to the 11th floor and walked to a freight elevator near Bank of America, whose money exchange center there is not open to the public. After the freight elevator doors opened, the robbers confronted seven people in the elevator, including the two Brink's security guards, who were delivering six currency bags to the bank, said Chief Frank Fox of the Port Authority police. He said the bags contained more than $3 million in cash, including some foreign currency.

The police said the robbers seemed to know what they wanted. One robber held a gun, telling everyone that they would not be hurt if they remained calm. Another grabbed a gun from one of the security officers and told all the passengers to get down.