Institutions across the US were shut down Thursday due to bomb threats sent in emails. Each email claims a bomb has been placed in the building and the sender’s “man” is watching the area, demanding a ransom in bitcoin. Police say they believe the threats to be a hoax ‒ but are taking precautions nonetheless.

"We are aware of the recent bomb threats made in cities around the country, including in Hampton Roads, and we remain in touch with our law enforcement partners to provide assistance," Norfolk FBI spokesperson Christina Pullen told the Virginian-Pilot in an email Thursday afternoon. "As always, we encourage the public to remain vigilant and to promptly report suspicious activities which could represent a threat to public safety."

The VP reported that seven locations in Norfolk alone had been shut down due to emailed bomb threats, plus others in neighboring cities like Hampton Roads and Virginia Beach.

Some of the emails have the subject line "Think Twice."

My buddy just had to evacuate his office building bc of a bomb threat. They’re asking for #BTC in return for not detonating. Idiots pic.twitter.com/2AW3Pi8mAR — Łitecoin Pirate (@LTC_Pirate) December 13, 2018

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Scores of institutions have been shut down for the same reason: an email in which the sender claims to have set a bomb inside the structure and to have their "man" nearby "watching the situation around the building."

The sender then demands a ransom in $20,000 worth of bitcoin by the end of the day, providing a BTC address.

Slightly different versions of the email have been reported, with small changes in wording, such as the material the bomb is reportedly made out of.

So I actually just got a bomb threat in my work email today ordering me to send the person $20,000 via bitcoin or they will blow up my place of work…. 2018 is wild pic.twitter.com/sn0vVLwe6v — Ryanocerous Grant (@TheeRyanGrant) December 13, 2018

​However, police across the country have urged that "the email is not a credible threat," according to a notice sent out to University of Washington staff.

"We are currently monitoring multiple bomb threats that have been sent electronically to various locations throughout the city," the New York Police Department's Counterterrorism Division said on Twitter. "These threats are also being reported to other locations nationwide & are NOT considered credible at this time."

Police further urge people not to pay the ransom.

Some of the affected locations include universities, courthouses, newspaper offices and corporate offices in New York, New York; Olympia and Seattle, Washington; Boise, Idaho; San Francisco, California; State College and Philadelphia, Pennsylvania; Orlando and Palm Beach, Florida; and Park City, Utah, among numerous other locations.

SCAM ALERT: There is a rampant hoax email being distributed across the country of a bomb threat making demands for money. Emails began locally around 1 pm. We do NOT believe these emails have any validity and direct you to delete email. Do NOT send money. More info coming soon — Grand Rapids Police (@GrandRapidsPD) December 13, 2018

​Streets in Washington, DC, were shut down as well, with police blocking road traffic and advising pedestrians to stay indoors.

© Sputnik / Police blocking 16th St NW in Washington, DC near Farragut Square

Police on K Street near the White House told a Sputnik reporter they were "working on a bomb threat" late Thursday afternoon. The all-clear notice was given not long after.