The FBI's counterterrorism division is leading the investigation Thursday into the packages and the agency says it's possible additional packages were mailed to other locations.
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Who got what, when: A timeline of when the bombs were found
A number of similar crude explosive devices have been sent since Monday to former President Barack Obama, Hillary Clinton, other top political figures and CNN's New York offices.
Authorities find 2 packages intended for Biden as manhunt ensues
Authorities have now found two packages addressed to former Vice President Joe Biden that are similar in appearance and contain potential explosive devices that resemble the others sent earlier this week to prominent critics of President Donald Trump and CNN, a law enforcement official said Thursday.
