The FBI is working with police to identify the source of a social media threat that prompted authorities to respond to John Hancock Tower in Boston's Back Bay Thursday morning.
Authorities said they received a call shortly before 7:30 a.m. for an investigation at 200 Clarendon St.
Numerous police cruisers could be seen outside the tower Thursday morning.
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The threat was made on social media and police said they do not know what kind of threat it was. Shortly before 10 a.m., police said the threat had been determined not to be credible. Police units are now clearing the scene.
In a statement issued an hour later, police said they found the incident to be "an uncorroborated threat of unknown reliability."
Police said they have increased their uniformed presence in the area, and all appropriate local, state and federal authorities are coordinating to identify the source of the threat. They said they will continue to monitor the situation.
The FBI said its Joint Terrorism Task force was working with local authorities to identify the source of the threat.
No injuries were reported.