From the Metrowest Daily News:
Police are searching for the car of a man a security guard said pointed a gun at him on Rte. 9 early this morning. At 12:36 a.m., a security guard with the company Securitas came to the station to report that a man had just threatened him.
The incident reportedly happened while the security guard was driving his van on Route 9 in the area of Central Street. You can read more in this article by the MWDN.