The FBI continues its investigation Thursday into multiple suspicious packages that were mailed to prominent Democratic figures over the last several days.
The packages, which were all mailed in manila envelopes and contained "potentially destructive devices," are being sent to the bureau's laboratory in Quantico, Virginia, for more testing.
The FBI is looking into packages addressed to former President Barack Obama, former Secretary of State Hillary Clinton as well as other current and former Democratic officials, a Democratic donor and CNN.
A former investigator for the U.S. Secret Service told the Associated Press that the FBI will be searching for any DNA or fingerprints left on the packages by the person who sent them. He said investigators will also track how each package went through the postal system and take apart the devices to see if the components match other explosive devices recovered from previous incidents.
While speaking at a campaign rally in Wisconsin Wednesday evening, President Donald Trump called for unity and said anyone found responsible will be brought to justice.
"Any acts or threats of political violence are an attack on our democracy itself. ... Such conduct must be fiercely opposed and firmly prosecuted," President Trump said.
The FBI warned the public to remain vigilant because more suspicious packages could've been mailed out. The U.S. Postal Service advises not opening any letters or packages that don't have a return address, use excessive postage or have protruding wires.
Additional reporting from Newsy affiliate CNN.