Following the incident, Boudreau was taken to Southern Maine Health Care in Biddeford, where she later died.
Police say she attacked Boudreau with a knife near the ice cream freezers inside the market just before 3 p.m.
A 59-year-old woman, identified as Wendy Boudreau of Saco, was seriously injured in the attack and pronounced dead at Southern Maine Medical Center.
Shoppers who witnessed the bloodbath inside this Shaw’s grocery store took down MacCalister before she could get away.
The two women did not appear to know each other, a police spokesman said, and investigators were working to identify a motive.
Colin Esposito, who was at the store shortly after the attack, tells WCSH that he saw a purse lying on the ground next to a “massive” pool of blood near the frozen food section.
Her first court appearance will likely be Thursday or Friday.
According to officials, 31-year-old Connor MacCalister, is currently being held on a murder charge from Wednesday’s stabbing inside Shaws in Saco.
An autopsy is scheduled for Thursday at the Maine State Medical Examiner’s Office in Augusta.