(CNN) Authorities across four countries are trying to learn who sent dozens of email bomb threats Thursday afternoon, causing anxiety and business disruptions but no reported violence. Similar threats were sent earlierIt is unclear whether Thursday's threats could be related to a series of hoax bomb threats sent since late August via an online messaging service to recipients in multiple states. The San Francisco Police Department responded to reports of bomb threats at locations throughout the city. Pennsylvania State Police are "investigating some bomb threats in the eastern part of the state," a department spokesman fold CNN. And the Australian Cyber Security Centre (ACSC) has alerted a "widespread bomb threat email campaign."

Source: CNN December 14, 2018 06:29 UTC