Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. Law Enforcement: Wave of Bomb Threats Emailed Across US, but None Credible by Reuters MILWAUKEE/LOS ANGELES -- A rash of bomb threats were circulated via email on Thursday targeting dozens of businesses and public buildings across the United States, but the credibility of those threats could not immediately be ascertained, law enforcement officials said. Police departments in several U.S. cities said on Twitter that local businesses had received a bomb threat in an email demanding payment in bitcoin currency. Among the cities where bomb threats were reported by authorities on official Twitter accounts were New York, Detroit, San Francisco, Oklahoma City, Denver and Raleigh, North Carolina. The New York City Police Department was investigating what a spokesman described as an "email chain" sent to businesses around the city threatening to set off an explosive device if payment was not made to an electronic currency account. The spokesman said he did not know whether similar threats and demands had been received elsewhere and was unaware whether any real bombs had been discovered. Police in Madison, Wisconsin, tweeted an image taken of one email threat found to be circulating that said in part: "Good day. There is an explosive device (lead azide) in the building where your company is conducted. It is assembled according to my guide. It is compact and it is covered up very carefully. It can not damage the structure of the building, but in case of its explosion you will get many wounded people." Police in Cedar Rapids, Iowa, reported similar email threats received by several businesses there but had found "no credible evidence any of these emails are authentic." The FBI has launched a query into the matter but the authenticity of the latest batch was not immediately confirmed, a law enforcement official told Reuters. "We are aware of threats being made in cities across the country," Rukelt Dalberis, an FBI spokesman in Los Angeles, told Reuters separately. "We remain in touch with our law enforcement partners. We encourage the public to remain vigilant and report suspicious activities that could represent a threat." Multiple U.S. law enforcement sources told Reuters that no actual explosives had surfaced in connection with any of the threats within the first hour of the scare. Previous threats A similar wave of emailed hoax bomb threats in December 2015 prompted officials in Los Angeles to close the city's public school system, a move that national law enforcement officials later criticized as an overreaction. That threat came two weeks after a married couple inspired by Islamic State killed 14 people at a California county office building in a shooting rampage. A teenager with dual Israeli-U.S. citizenship was arrested in Israel in March 2017 for making bomb threats to more than 100 Jewish organizations and Jewish community centers (JCCs) in dozens of U.S. states over several months.