Updated at 11:09 p.m. ET
Two men on a United Airlines flight from Chicago to Amsterdam were questioned by Dutch authorities after U.S. officials found a cell phone taped to a Pepto Bismol bottle and a knife and box cutter in checked luggage connected with the men, a law enforcement official said.
The official identified the men as Ahmed Mohamed Nasser al Soofi and Hezam al Murisi. Al Soofi had a Michigan address, the official said, but it was not immediately clear where the two men were from.
As of Monday night, FBI agents had visited the Detroit neighborhood where several addresses were found for variations of al Soofi's name, according to neighbors who declined to give their names to The Associated Press.
ABC News, which first reported the incident Monday, said al Soofi was from Detroit and that both he and al Murisi were charged in the Netherlands with "preparation of a terrorist attack," but U.S. officials would not confirm that.
Another law enforcement official said, as of Monday night, the men had not been charged with anything in the U.S. CBS News Justice correspondent Bob Orr reports U.S. officials are still trying to determine whether this is a real threat.
The law enforcement officials spoke on condition of anonymity to discuss the ongoing investigation and sensitive security issues.
Al Soofi was questioned as he went through security in Alabama on his way to Chicago, according to one of the officials. He told the Transportation Security Administration authorities he was carrying a lot of cash. Screeners found $7,000 on him but he was not breaking any law by carrying that much money. Officials also found multiple cell phones taped together and multiple watches taped together in his checked baggage.
Al Soofi was supposed to fly from Chicago to Washington Dulles International Airport in Virginia, and then on to Amsterdam, the official said. But when he got to Chicago, he changed his travel plans to take a direct flight from Chicago to Amsterdam. Al Murisi also changed his travel plans in Chicago to take a direct flight to Amsterdam, raising suspicion among U.S. officials. Federal Air marshals were on the flight from Chicago to Amsterdam, a law enforcement official said.
Homeland Security spokeswoman Amy Kudwa said once officials found suspicious items in luggage associated with two passengers on Sunday night's flight, they notified the Dutch authorities.
"The items were not deemed to be dangerous in and of themselves," Kudwa said. She would not identify the two passengers.
It is not illegal to carry knives or taped cell phones and watches in checked baggage.