Authorities were conducting an investigation Wednesday after a bomb-laden package exploded at a university in the US city of Boston, leaving an employee with minor injuries. 

In a statement, the Boston Police Department said police officers responded to a call Tuesday evening at Northeastern University in the Massachusetts capital "for a report of a package that had exploded."

The 45-year-old employee, who was not identified, was taken to the hospital for treatment of "minor injuries to his hand."

A police bomb squad found and neutralized a second package, the department added.

The Federal Bureau of Investigation (FBI) is assisting in the probe. Authorities did not immediately provide information on a possible motive.

CNN cited a federal law enforcement source as saying that the package contained a note criticizing Facebook founder Mark Zuckerberg and ties between academic institutions and virtual reality developers.

The package was delivered to Northeastern's Holmes Hall, which houses the Immersive Media Labs virtual reality center, local media reported.

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