Obama aware of threat since Thursday night

President Obama was alerted late Thursday night of a possible terrorist threat that has grounded three aircraft in the U.S., according to a statement from White House press secretary Robert Gibbs.

Gibbs said the suspicious packages were first discovered on cargo planes leaving an airport near London, England, and were allowed to cross the Atlantic before being delayed by authorities in the U.S.

Two UPS cargo planes are being searched in Philadelphia, while another is in Newark. Authorities have confirmed that a printer toner cartridge was manipulated, appeared to have wires attached to it, and was covered in white powder. The cartridges tested negative for explosives, according to an FBI spokesman who spoke to Bloomberg News.

Gibbs said the packages originated from Yemen.

He also stated that Obama has directed the Department of Homeland Security and other enforcement agencies to “determine whether these threats are a part of any additional terrorist plotting.”