US CAPITOL POLICE are investigating the discovery of at least two suspicious packages in Senate office buildings and “the individual who delivered them is being questioned,” Sergeant at Arms Terence Gainer said today.

Gainer said in an email the packages were delivered to at least two Senate offices. Yesterday the Secret Service intercepted a letter addressed to President Barack Obama that contained a “suspicious substance”.

A law enforcement official said the letter is very similar to one recently mailed to Mississippi Republican Senator Roger Wicker. The Senator’s letter tested positive for the poisonous substance ricin and preliminary tests on Obama’s letter indicate it may also be present on that.

The letters were received at separate facilities that sort mail addressed to the White House and Capitol Hill. The mail facilities are not located on the main White House and Capitol Hill complexes. It was not clear whether there was a connection between the letters and the packages.

Other officials said one of the packages had been discovered in the Russell Building, and the second in the Hart office building. CNN reported that the first floor of the Hart building was evacuated shortly after noon and a man in the area was being questioned by police.

Word of the suspicious packages comes amid already heightened tensions in Washington and across the country since the deadly bombings on Monday at the Boston Marathon that killed three people and injured more than 170. Law enforcement officials haven’t said whether they believe the letters are related in any way to the Boston bombings.

- Additional reporting by Michelle Hennessy.

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