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  This image provided by CBS News shows a printer toner cartridge with wires and powder found in a package aboard a plane searched in East Midlands, north of London. US officials said preliminary tests indicated the packages contained the powerful industrial explosive PETN, the same chemical used in the Christmas attack involving a Detroit-bound airliner. (CBS News,AP)
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  Investigators board a United Parcel Service jet isolated on a runway at Philadelphia International Airport in Philadelphia. Law enforcement officials are investigating reports of suspicious packages on cargo planes in Philadelphia and Newark. (Matt Rourke, AP)
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  Law enforcement officials are investigating reports of suspicious packages on cargo planes in Philadelphia and Newark. (FOX News Channel, AP)
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  Parts of a computer printer with explosives loaded into its toner cartridge found in a package on board a cargo plane coming from Yemen, in Dubai, United Arab Emirates. (Dubai Police, AP)
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  Dubai police say the bomb, discovered in the ink cartridge of a computer printer in a shipment of air cargo from Yemen bound for the United States, contained the powerful explosive PETN and bore the hallmarks of al-Qaeda. Dubai Police, AP)
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  Parts of a computer printer with explosives loaded into its toner cartridge found in a package on board a cargo plane coming from Yemen, in Dubai, United Arab Emirates. (Dubai Police, AP)
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  Dubai police say the bomb, discovered in the ink cartridge of a computer printer in a shipment of air cargo from Yemen bound for the United States, contained the powerful explosive PETN and bore the hallmarks of al-Qaeda. (Dubai Police)
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  The bomb, discovered in the ink cartridge of a computer printer in a shipment of air cargo from Yemen bound for the United States, contained the powerful explosive PETN and bore the hallmarks of al-Qaeda. (Dubai Police AP)
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  Ibrahim Hassan al-Asiri who, according to US officials, is the suspected bomb maker behind the underpants bomber and prime suspect in the latest Yemen mail bomb plot. (Saudi Arabia Ministry of Interior, AP)
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  Cantor Michelle Fricker Friedman and Rabbi Michael Zedek, of Emmanuel Congregation, which was one of the targets of a foiled terror plot. (David Banks, AP)
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  Transportation security officer place luggage on an X-ray machine at Dulles International Airport (Jose Luis Magana, AP)
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  A computer printer with explosives loaded into its toner cartridge found in a package on board a cargo plane coming from Yemen, in Dubai, United Arab Emirates. (Dubai Police, AP)
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  The bomb, discovered in the ink cartridge of a computer printer in a shipment of air cargo from Yemen bound for the United States, contained the powerful explosive PETN and bore the hallmarks of al-Qaeda. (Dubai Police AP)
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  The bomb, discovered in the ink cartridge of a computer printer in a shipment of air cargo from Yemen bound for the United States, contained the powerful explosive PETN and bore the hallmarks of al-Qaeda. (Dubai Police AP)

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