CHICAGO -- Private security workers at O'Hare International Airport were accused of letting a man pass through a checkpoint with several knives and a stun gun. Subash Gurung, 27, of Chicago was arrested trying to board a United Airlines flight to Omaha, Neb., on Saturday night. He was charged with unlawful use of a weapon and attempting to board an aircraft with weapons, both state misdemeanors. After being released on bail on those charges early Sunday, FBI agents arrested him again when he returned to O'Hare for his checked-in luggage and was charged with a federal felony count of attempting to carry a weapon on an aircraft. City officials said seven security workers, including a supervisor, failed to detain the Nepal-born Gurung after two folding knives were discovered in his pocket when he passed through a metal detector. The workers did not notice seven other knives, a stun gun and a can of Mace when Gurung's bag went through an X-ray machine. Instead, they were found by United Airlines employees in the gate area who searched Gurung's carry-on bag. ``Something obviously went seriously wrong here, and we're trying to find out if it's the employees' fault,'' said Monique Bond, spokeswoman for the Chicago Department of Aviation. ``If weapons were confiscated, he should never have been let through security.'' It was not immediately clear why Gurung tried to take the weapons aboard the airplane. In a statement, the FBI said there was no allegation that terrorism was involved. The screening workers were hired by an Atlanta-based security company. The Federal Aviation Administration is investigating the incident. Although it was unclear whether the security workers had been fired or suspended, they no longer have the city-issued badges allowing them to work at O'Hare. Lawmakers said the incident would provide ammunition in debates over anti-terrorism legislation pending on Capitol Hill. Democrats want the federal government to take over airport security, while President Bush and many Republicans say the security job should stay in private hands. U.S. House Speaker Dennis Hastert, R-Ill., said officials would not have been able to fire the seven employees if they had enjoyed the civil service protection of federal employees. But Rep. Jan Schakowsky, D-Ill., maintained that the security system would never work unless those running it were federal employees, ``like the Customs Service, like the FBI.''