White House: "We will not be terrorized"

U.S. congressional police clear parts of two Senate office buildings Wednesday over concerns over suspicious letters and a package.

Officials are looking into a suspicious package and envelopes and are questioning an individual in that matter. Tests on one suspicious item came back negative and one building was reopened.

White House spokesman Jay Carney says there are also concerns over a letter address to President Barack Obama.

(SOUNDBITE)(English) JAY CARNEY, WHITE HOUSE PRESS SECRETARY SAYING:

"There was a letter sent to -- addressed to the President that at an offsite mail facility was noticed to have contained a suspicious substance, and tests were undertaken. "

In Boston, authorities may have made a breakthrough in the investigation the Marathon bombing that killed three people and injured 176.

Sources tell Reuters investigators believe they have identified a suspect from video and an official announcement is expected later.

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