Two heartless thieves assaulted and robbed an elderly woman for her purse inside of a Bronx building, cops said.

The suspect followed the defenseless 83-year-old into the Longfellow Avenue apartment building in Tremont around 5:50 p.m. Tuesday and demanded her purse, police said.

But when she refused they knocked her to the floor and wrestled it off of her, according to police.

She suffered a head injury from the fall and was taken at St. Barnabas Hospital for the laceration and later released, authorities said.

The duo was caught on surveillance video speed-walking away from the scene, one in a red hoodie, the other wearing black.