Don't attempt to assault anyone, they might have a gun and shoot you... here is a case of

another assault that ends in death of the assailant

A Boston police officer has shot and killed a Massachusetts man who had been under surveillance by the FBI's Joint Terrorism Task Force, ABC News has learned.

The FBI had been tracking 26-year-old Usaama Rahim for several weeks, and authorities are looking into whether he may have been radicalized by ISIS propaganda online, law enforcement sources said.

An officer and an FBI agent approached Rahim a little after 7 a.m. today in the parking lot of a CVS in Roslindale, Massachusetts, police said. The suspect then "came at the officers" with a "military-style knife," police said.