Boeing was forced to evacuate part of its factory near Philadelphia today after a threatening note was found in a bathroom, the Associated Press reported.
The AP said about 500 employees were ordered to leave the building where the H-47 Chinook helicopter is made. Police searched the area but didn't find anything suspicious.
Reuters reported that the threat was telephoned to the sprawling facility on the outskirts of the city. The nature of the threat was not revealed.
Some US media reports claimed it was a bomb threat, but Boeing spokesman Damien Mills and police would not comment on the reports, the Agence France-Presse reported.
"Early this morning around about 7:30 am (1130 GMT), Boeing received notification of a threat at one of its facilities at Ridley Park," Mills said.
"In the interest of safety, we evacuated employees, notified the local authorities and contacted Delaware County Police.”
The incident coincided with the 11th anniversary of the September 11 terrorist attacks on the World Trade Center and Pentagon, and comes after the shooting in New York last month when a man shot dead a former co-worker near the Empire State Building.
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