A 71-year-old woman was killed by a stray bullet in a broad-daylight Bronx shooting that also left a younger woman injured Thursday, cops and sources said — with surveillance video capturing the moment one of the victims was struck down in the street.

The shocking footage, obtained by The Post, shows a person who appears to be the older of the two victims falling to the ground at a crosswalk in Mott Haven — and two people running away in different directions just moments later.

The bullets flew on East 138th Street near Brook Avenue in Mott Haven just after 12:30 p.m., striking the septuagenarian in the back and hitting a 34-year-old woman in the arm, authorities said.

Both were taken to Lincoln Medical Center, where the older woman — an innocent bystander — was pronounced dead, according to cops and law enforcement sources. 

The younger woman, who suffered non-life-threatening injuries, was taken to the same hospital, police said.

It was not immediately clear whether she was targeted in the gun violence. 

The gunman ran off, heading west on East 138th Street, police said.

Cops described the suspect as a man with dark skin and dreadlocks, wearing all black, authorities said.