Side Chick Tries To Escape Down The 3rd Floor Fire Escape, Girlfriend Pushes Her Off! (UPDATED)

Shocking video captures the moment a woman fell from a Bronx fire escape while tussling with a man through a window — all part of a wild incident that later ended with the guy killing another person, police and sources said Monday.

Cops at first said 35-year-old Erica Morel just fell from a third-floor fire escape at the Marion Avenue building in Fordham Manor around 3:15 p.m. Sunday, leaving her in critical but stable condition.

But police and law-enforcement sources revealed to The Post on Monday exactly why and how Morel plunged from the building — adding that the twisted incident appears to have led to a death hours later.

A police source said Morel is believed to have been feuding with another woman over money and drugs and went to the apartment of the lady’s boyfriend, Dwayne Murray, 29, to confront her there.

When the woman wouldn’t let Morel in, “that’s when Morel climbs the fire escape with a knife,’’ the source said.

“She’s banging on the window, causing it to break. Dwayne came to the window, she backed away, lost her footing and fell.”

A dramatic 15-second video taken by a bystander, posted to Facebook, widely shared online and confirmed by police as being from the incident shows Morel scrapping with Murray through the window before she fell.

“What the f–k,” the bystander says during the incident, according to the video.

Morel hit the fire escape one story below before belly-flopping to the ground, the footage shows.

She was taken to St. Barnabas Hospital in critical but stable condition. Her condition was later upgraded to stable, authorities said.

Meanwhile, Murray was treated at the scene for injuries from the broken window — but that wasn’t the worst of it for him that day, the police source said.

People soon started “threatening him and accusing him of pushing Erica out the window,’’ the police source said.

One of the people allegedly hassling Murray was Curtis Nicholas, 37, a member of the Gorilla Stone Gang, a subset of the Bloods, according to cops.

Nicholas then turned up seven hours later fatally stabbed — and police have now charged Murray in his death, the NYPD said.