WASHINGTON D.C. -- HAZMAT swarmed the congressional mail processing center in Maryland.

Officials say letters set to be delivered to the White House and President Obama tested positive for ricin.

It is important to note, the results came from field tests which are often inaccurate. The letters are being tested again in a secure lab to be safe.

"Any time a suspicious powder is located in a mail facility, it is tested," said Jay Camey, White House Press Secretary. "These tests are undertaken at remote sites to mitigate the risk both to those recipients and to the general population."

Ricin comes from castor beans and can be deadly if ingested or inhaled.

The FBI says there is no indication the letters are connected to the Boston attack.