RIDLEY PARK, Pa. (AP) – The part of a Boeing factory near Philadelphia that produces the H-47 Chinook helicopter was evacuated Tuesday after a threatening note was found, a company spokesman said.

Neither the company nor police divulged what was in the note or who left it, but it forced several hundred employees to leave the sprawling plant between 7:30 a.m. and 8:30 a.m.

“The threat related to one of our production facilities,” said Boeing spokesman Damien Mills. The Ridley Park factory also produces the V-22 Osprey.

Another spokesman, Andrew Lee, said first-shift workers were being sent home but Boeing was hopeful second-shift workers would be on the job in the afternoon.

“The investigation into the threat is still continuing inside the building,” Lee said.

Doc Price, 63, who works as an aircraft tech on the Chinook, said they got word to leave the building early.

“They just said, ‘Everyone, out of the building,”’ he said.

Asked if there was any word on who left the note, Price said he didn’t know, but added that “somebody probably made a major mistake.”

Last year, federal agents raided the facility and charged more than three dozen people with distributing or trying to get prescription drugs, among them powerful painkillers.

In November 2008, Boeing temporarily shut down two production lines after a plastic cap was found in the fuel line of an in-production Osprey. The company later submitted a corrective action plan and restarted production.

In May 2008, the factory was shut down when a disgruntled employee used his work-issued wire cutters to sever about 70 electrical wires in a nearly finished Chinook. That employee, Matthew Montgomery, of Trevose, pleaded guilty to destroying property under contract to the government. Authorities said he was upset about a job transfer.