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STATE COLLEGE, Pa. (CBS/AP) — A wave of bomb threats being reported around the country — including across the Delaware Valley area — appear to be a hoax. Authorities say around 30 bomb threats have been received throughout Montgomery County on Thursday and several have also been reported in Chester County.

The Cancer Treatment Center of America in Philadelphia also received a bomb threat, as well as Penn State’s main campus.

Penn State University notified students via a text alert about threats to a half-dozen buildings and an airport on its main campus in State College, Pennsylvania. In an update, the school said the threat appeared to be part of a “national hoax.”

“Like many other law enforcement agencies across the country, we have received several reports of bomb threats being made via email. At this time, we don’t have any reason to believe that any of these threats are credible. Still, we ask that folks remain vigilant, and to report any suspicious activity immediately,” Philadelphia Police said in a statement.

Authorities in Camden County say three threats were received there. And in Bucks County, Reedman Toll Auto World also received a threat.

The FBI is reportedly involved in the investigations and the threats are coming in through email.

“The FBI is aware of the recent bomb threats made in cities around the country, and we remain in touch with our law enforcement partners to provide assistance. As always, we encourage the public to remain vigilant and to promptly report suspicious activities which could represent a threat to public safety,” the FBI said in a statement.

Law enforcement agencies across the country dismissed the threats, saying they were meant to cause disruption and compel recipients into sending money and were not considered credible.

Some of the emails had the subject line: “Think Twice.” They were sent from a spoofed email address. The sender claimed to have had an associate plant a small bomb in the recipient’s building and that the only way to stop him from setting it off was by making an online payment of $20,000 in Bitcoin.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)