A rampaging gunman killed an elderly man, his son-in-law and grandson in their apartment Thursday, then fell off a fire escape to his death while trying to flee the scene, police said.

Hector Quinones — who knew one of his victims from prison, police said — wounded a woman and terrorized another family member who found him in their third-floor walkup apartment.

Police found Carlos Rodriguez Sr., 52; and his son, Carlos Rodriguez, 24; shot to death in an apartment bedroom. Rodriguez Sr.'s father, Fernando Gonzalez, 87, was dead in a bathroom, possibly after being stabbed with a bloody knife recovered in the kitchen, they said.

Also discovered in the apartment in the rear of the walk-up building were a large stash of heroin and a semiautomatic handgun believed to be the murder weapon, chief police spokesman Paul Browne said.

Police said Quinones, 44, had recently been released from prison after serving time for manslaughter, and had known the elder Rodriguez from prison in the 1990s. The elder Rodriguez had served sentences for several drug convictions, police said.

The family lived on a busy street of bars and eateries in a tree-lined residential neighborhood a few blocks from Central Park and the American Museum of Natural History.

Giselle Rodriguez — who was married to Carlos Rodriguez Sr. and the mother of the 24-year-old man — and her daughter came upon Quinones after the men had been shot, police said.

Quinones held both women at gunpoint before the daughter, Lyanis Rodriguez, broke free and locked herself in the bedroom with her father and brother's bodies, police said. Quinones shot and wounded Giselle Rodriguez — who was hospitalized in stable condition Thursday night — before both women managed to escape the apartment, police said.

Quinones fell to his death from a fire escape into a cement courtyard below, police said. He was wearing latex gloves underneath a pair of leather gloves, they added.

The shootings rattled the upscale neighborhood, as pizzeria owners and priests watched the wounded woman wheeled into an ambulance.

"It's just horrible," said Rick James, who grew up with the younger Rodriguez. "Your home is your most sacred place."

He said he had played video games with his friend a few days ago.

"He was a good kid. He definitely didn't deserve what happened," he said.

Police had the entrance to the building and part of the block cordoned off. Scores of onlookers crowded the sidewalks, and dozens of police cars lined Amsterdam Avenue.

This is a great, yuppified neighborhood," said Gene Silvers, who was pumping air into his bicycle tires across the street from the shootings. "Not dangerous."

Hispanic neighbors planned a Spanish-only prayer service for the victims later Thursday.

Hector O'Neal, who said he was the family's landlord, said police had asked him not to speak about "la familia familia Rodriguez."

"I can't talk to anybody right now," he said.

Dimitrios Vezyrakis said the family were "nice people, just normal people who came in for pizza" across the street.

Darryl Gamble, who owns a women's clothing boutique on the ground floor, said he heard no commotion coming from the apartments.

"I think that most of the tenants have been there for years," Gamble said. He said he had no problems with his neighbors, outside of "the usual, New York noise, a few leaks."

Click here for more on this story from MyFoxNY.com.