The massacre occurred Thursday afternoon near a string of upscale shops on Manhattan's Upper West Side. Police said the attack apparently stemmed from botched drug ripoff.
"There is a significant amount of heroin found in the apartment," Police Commissioner Raymond Kelly told the Daily News.
Police said Hector Quinones, 44, shot and killed Carlos Rodriguez Sr., 52, and his 24-year-old son, Carlos Rodriguez Jr., then stabbed to death the younger Rodriguez's grandfather, Fernando Gonzalez, 87, according to reports in the Daily News and the New York Post.
The elder Rodriguez's wife, Gisela Rodriguez, 49, and her daughter, Leyanis, 28, walked in on the carnage. Quinones heard keys in the lock and opened the door for the women, police said.
He shot the mother, who was grazed on the head by a bullet but managed to run from the apartment. The killer was just about the grab the daughter when his low-slung pants fell down and he tripped, the Post said. That gave the young woman the chance to run into a back room, where she found the bodies of her brother and father.
Quinones yanked up his pants and scrambled after Leyanis Rodriguez, who climbed onto a fire escape, screaming for help to construction workers on the roof of a nearby building, the Post said. The attacker followed her onto the fire escape, but once again his drooping pants fell and he tripped, plunging three stories to his death.
Estella Carrino, who manages a street-level bicycle store in the building, said she heard the body hit the ground.
"He had no jacket on and his pants were down. He was very dead," she told the Daily News.