SACRAMENTO (CBS13/AP) – Authorities nationwide are monitoring multiple bomb threats reportedly aimed at businesses, schools, and residents across the country.

Several law enforcement agencies in the Sacramento region received reports of the threats, which were sent electronically to numerous locations and do not appear to be credible.

The El Dorado County Sheriff’s Office says anyone receiving an email bomb threat demanding “bitcoin”, please report it to them. Some of the hoax emails had the subject line: “Think Twice.”

The FBI also issued a statement:

“We are 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,” the FBI said in a statement. “As always, we encourage the public to remain vigilant and to promptly report suspicious activities which could represent a threat to public safety.”

Across the country, some schools were closed early and others were evacuated because of the threats. Penn State University noticed students via a campus alert. Near Atlanta, people were ushered out of a courthouse.

Sources told CBS News the threats appear to be extortion attempts for money or cause disruption.

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