Suspected explosive devices were sent to former Secretary of State Hillary Clinton and former US President Barack Obama, the US Secret Service has said.
It comes two days after a bomb was found at the home of liberal philanthropist and financier George Soros in the suburbs of New York City.
The devices were discovered by technicians who screen mail sent to the former US officials.
It was not immediately clear where the suspicious packages were found.
According to a statement from the US Secret Service, the first package recovered was addressed to Mrs Clinton late on 23 October.
“Early this morning, October 24, 2018, a second package addressed to the residence of Former President Barack Obama was intercepted by Secret Service personnel in Washington, DC,” the statement adds.
“Both packages were intercepted prior to being delivered to their intended location. The protectees did not receive the packages nor were they at risk of receiving them.”
The FBI in New York said they were aware of the suspected packages, and are aiding in the investigation.
A spokeswoman for Mr Obama declined to comment on the incident, and referred reporters to the Secret Service statement.
The suspected explosive devices come two days after a confirmed pipe bomb was discovered in a mailbox at the home of Mr Soros.