Using these tips from the Department of Homeland Security, you can identify any suspicious material sent to you by post.

After sending 12 potential explosive devices to prominent Democrats, law enforcement officials continue to search for post offices on Friday after warning the public that more parcels may be released.

"This is to be taken with the utmost seriousness," New York Police Commissioner James P. O'Neill told reporters at a press conference Thursday when he was asked if the mailings were part of a joke. "We treat them as alleged explosives."

On Friday morning, the New York City Police Department closed a crossroads of Manhattan traffic and pedestrians over another possible explosive package found in a post office. The FBI confirmed that it was an eleventh package, "similar to the others," addressed to Senator Cory Booker, a New Jersey Democrat.

So far none of the suspicious packages has hurt anyone.

Officials were looking for a mailing center in Florida on Thursday night for possible clues as to where the packages came from. A horror at the Time Warner Center in New York caused more panic following reports of unattended packages.

We now know the following.

What do we know about Package 11?

The FBI confirmed that they had found a suspicious package "similar to the others" addressed to Democrat Sen. Cory Booker. [19659047] The #FBI has confirmed that an 11th package was found in Florida, much like the others, addressed to Senator Cory Booker

– FBI (@FBI) October 26 2018