CHICAGO (WLS) -- Dozens of sites in the Chicago area received bomb threats that authorities believe to be part of a nationwide bomb hoax and extortion attempt.
Federal authorities and local law enforcement across the country were investigating hundreds if not thousands of hoax threats made to various targets including schools, public offices and commercial buildings.
The threats in the Chicago area were sent primarily to locations in Chicago and the western suburbs.
Anthony Guglielmi, chief communications officer for the Chicago Police Department, did not specify what locations in Chicago received threats but said that CPD was working with federal partners to investigate the threats. There is no elevated risk to the city, he said.
In total, 43 email threats were reported to Chicago police, the I-Team learned later Thursday.
Aurora was the most heavily-targeted suburb to receive these threats. Earth Movers Credit Union in the 1700 block of North Farnsworth Avenue; City Hall, located at 44 East Downer Place; and Rush Copley Medical Center all received threats, police confirmed. The hospital is open and patient care has not been affected, though appropriate safety measures were implemented, including alerting the Aurora police, the hospital said in a tweet.
Bombs were not found at any of the locations targeted in Aurora, police said.
A building in Rosemont was evacuated after receiving a threat, police said. The threat was sent to an office building in the 9700 block of West Higgins Road at about 12:50 p.m. While police investigated the threat, the building's management set off the fire alarm. People were let back into the building once it was deemed safe, police said.
Another threat was emailed to a business in the 500 block of Division Drive in South Elgin, police said. The email stated that there was a bomb hidden in the building and instructed the company to send $20,000 to a bitcoin account by the end of the business day in order to avoid detonation of the explosive, according to South Elgin police.
About 2 p.m., a similar threat was sent to a business in the 300 block of North York Road, according to Elmhurst police.
Glen Ellyn police said one threat was sent to a business in the 900 block of Roosevelt Road.
The nature of the threats made follow a pattern of threats made across the country. In each reported incident, the target receives an email stating that there is an explosive hidden in the building and instructs them to send a large sum of money to a bitcoin account by the end of the business day in order to avoid detonation, authorities said.
"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."
The FBI is likely to become more involved as the number of locations that received threats grows, especially as the threats cross so many state lines, an FBI official told ABC News. Despite this, the threats are not believed to be credible, the official said. Because the sender asks for money to be sent electronically, the messages are believed to be part of an extortion attempt, authorities said.
Anyone who receives a threat is asked to contact local law enforcement.