An armed 70-year-old man shot at and injured a former co-worker at a Massachusetts business before killing himself in what authorities are calling an act of workplace violence.

Middlesex District Attorney Marian Ryan says the shooter waited for the other man to arrive at the Cambridge business before ambushing him outside with a 12-guage pump action shotgun at about 7:45 a.m. Thursday.

The victim used his briefcase to shield his head and was struck by debris that flew off the brick building. Ryan says the victim was not struck by gunfire and was taken to the hospital with injuries not considered to be life threatening.

The shooter returned to his car and killed himself.

Ryan says the victim had been involved in the decision to fire the shooter months ago.

No names were released.

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