Masked gunmen staged a daring predawn raid at a Lufthansa airlines cargo hangar at Kennedy Airport today, handcuffed nine employes and fled in a black van with about $3 million in cash and up to $500,000 in other loot -- making it among the largest robberies in U.S. history.

The money -- five shipments of U.S. currency -- was en route to Chase Manhattan Bank headquarters from a bank in Frankfurt, West Germany, according to a bank spokeswoman.

Police Capt. Ralph Combriati of the Port Authority, which operates the airport, said the gunmen took about $3 million in U.S. currency, Italian lira valued at $130,000, as well as gold, pearls, jewelry and checks.

Fort Authority police inspector William J. Cox said the American currency was "used" and therefore no serial numbers were available.

Cox said six, possibly seven, gunmen were involved and investigators did not know their identities.

Both Cox and Walter Yoos, the FBI agent in charge at the airport, said Lufthansa employes and others at the airport were being questioned to determine whether the gang had inside help. "This is being fully investigated." Cox said.

James Connolly, a Port Authority police spokesman, said the gang members gained entry to Building 261 at the airport at 3:10 am. by thrusting a gun into the face of one of the Lufthansa employes.

They forced the workers into an employes' cafeteria where they pistolwhipped one man and then feft the group handcuffed, according to Connolly.

"They were prepared. They had enough hadcuffs for all [the] employes," he said.

The gunmen then went back to the cargo holding area where they took some 15 bags containing the cash and jewels.

"It went off like clockwork. It was well-planned, well-organized and well-executed," Connolly said.

He said Port Authority detectives were trying to determine why a silent alarm system that would have alerted police failed to work.

The scope of the heist apparently ranks it among the nation's largest. On New Years Eve 1971, armed robbers ransacked vaults at the Hotel Pierre in New York and escaped with jewels and money valued at $5 million. The famous Brink's robbery of 1950 was worth $1.2 million. In a case that did not involve arms, a $10.2 million fund transfer was allegedly managed in the offices of Security Pacific National Bank in Los Angeles six weeks ago.