Shots struck and wounded two officers, and police returned fire. Vaughn was struck in the exchange, and he was rushed to the hospital, where he was pronounced dead.

The two wounded officers were also taken to the hospital and later released. One officer was shot in the elbow, and the other had been struck in the stomach. 

"The investigation that followed determined that the firearm utilized by Mr. Vaughn had been modified with an aftermarket machine-gun conversion device, commonly referred to as a 'switch,'" the department stated. "This modification enabled the firearm to discharge multiple rounds automatically with a single function of the trigger. Investigators also established that Mr. Vaughn was a convicted felon and, as such, was legally prohibited from possessing a firearm."

Investigations by the Massachusetts State Police Detectives Unit and the Bristol County District Attorney's Office found that the use of deadly force was justified. An investigation by the department's Shooting Investigation Team determined that the officers followed agency policies and procedures.

"Two members of our department were shot while carrying out their sworn duties, placing their lives in immediate danger," the department stated. "Their decision to employ deadly force was not made in a controlled or predictable environment; rather, it was a response to an active and immediate threat of deadly violence. …No officer begins a shift anticipating that they will be required to discharge their firearm in defense of their own life or the lives of others. It is an extraordinary responsibility, one that carries profound consequences for everyone involved."