A series of what appear to be unfounded bomb threats were made via email to organizations and individuals across the nation Thursday, grinding businesses to a halt and forcing the evacuation of numerous buildings containing thousands of people.

Thursday morning, emails went out to schools and businesses across the country demanding ransom payments in bitcoin. The University of Washington issued an alert, saying the emails were likely spam sent to numerous organizations around the country, and not a credible threat, but UW Police still swept buildings across campus.

UPDATE: 11:15 A.M. The University of Washington Police Department continues to investigate the email threats, but has determined there is no safety concern. UWPD has concluded sweeps of affected buildings. The FBI has also advised that the email is not a credible threat. UPDATE: 10:49 A.M. The University of Washington Police Department is aware of and investigating threatening emails sent to individuals on campus. Police are conducting sweeps of campus buildings as a precautionary measure. It appears to be a generic spam email that has been sent to other organizations around the country. If you receive such an email, notify UWPD at 206-685-8973.

Though officials are regarding the emails as spam and not credible threats, many organizations took precautionary steps to evacuate the areas to make sure everything was safe.

Several area businesses are receiving what appears to be a robo-email saying there is a bomb threat to their business unless they pay money in Bitcoins. We have found no credible evidence any of these emails are authentic. See CRPD Facebook for more details. #Scam — Cedar Rapids Police (@CR_Police) December 13, 2018

We are currently monitoring multiple bomb threats that have been sent electronically to various locations throughout the city. These threats are also being reported to other locations nationwide & are NOT considered credible at this time. pic.twitter.com/GowGG4oZ9l — NYPDCounterterrorism (@NYPDCT) December 13, 2018

The threats come just a day after Facebook’s Menlo Park, Calif. headquarters had to be evacuated briefly due to bomb threats.

Reports of the bomb threats as well as screenshots of the emails appeared on social media Thursday:

Bomb threat at Bronx H.S. of Science prompts evacuation of roughly 3,000 studentshttps://t.co/WpyazlKAJe pic.twitter.com/ekjGPS3v3u — New York Daily News (@NYDailyNews) December 13, 2018

The Bitcoin-spam-scammers have moved on from fake blackmail threats to fake bomb threats. So far no-one's paid anything to the address, and I suspect it'll stay that way. pic.twitter.com/N5MOdmu8Jm — Tom Scott (@tomscott) December 13, 2018

Well, that's a new one. I just got a random bomb threat via email, demanding bitcoin payment. Since I'm at the coffee shop now, I suppose I'm safe. #ransomemail pic.twitter.com/MTj6X56mjm — Lance King (@analogfusion) December 13, 2018