A former soldier chased after a man who flashed her twice during a morning jog before pinning him to the ground.
Mum-of-two Aia, 35, said the man dropped his pants while running towards her on a riverside road in Cambridge, Massachusetts, and tried to touch her arm last Thursday.
CCTV footage from across the street shows the moment Aia turned around and chased after the man to confront him.
She then held him onto the ground and asks onlookers to call the police, but no one seemed to offer help.
The man eventually ran away when she called 911 herself.