U.S. President Barack Obama makes a statement about the bombing at the Boston Marathon, at the White House April 16, 2013 in Washington, DC. Courtesy Getty Images.
Washington, DC -- The FBI says preliminary tests on a letter sent to President Barack Obama indicate the presence of poisonous ricin.
The letter is undergoing further testing because preliminary field tests can be unreliable, creating false positives.
The letter was intercepted at a facility away from the White House. It comes the day after officials said a letter sent to Sen. Roger Wicker tested positive for poisonous ricin. That letter to Wicker, a Republican, was intercepted at a Senate mail facility just outside Washington.
Read: Officials: 2nd Letter To Senate Tested For Ricin
Tensions have been high 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.