The attacks happened yesterday evening in Taunton – about 40 miles south of Boston.
Police say the attacker – a 28-year-old man – was shot dead by an off-duty officer.
He is believed to have stabbed two 80-year-old women at a home in the city, before crashing his car through the front of a Macy's store at a local mall and stabbing diners in a restaurant.
A motive for the attacks remains unclear, but state police say they haven't found any links to terrorism.
