Larry Celona, John Doyle, and Laurie Kamens, New York Post, December 18, 2009

A career criminal who slaughtered three members of a family in their apartment in New York’s trendy Upper West Side Thursday plunged to his death after tripping over his baggy pants.

The bloodshed began when the killer barged into the family’s third floor apartment and opened fire at around 1:45 p.m. Thursday, near a string of upscale shops.

Gunman Hector Quinones blew away 24-year-old Carlos Rodriguez Jr., and his father Carlos Rodriguez Sr., 52, and then repeatedly stabbed grandfather Fernando Gonzalez, 87, to death before the elder Rodriguez’s wife and adult daughter walked unwittingly into the carnage in the apartment they all shared.

As soon as Gisela Rodriguez, 49, and her daughter, Leyanis, 28, walked inside, Quinones, 44, opened fire again at the mother, grazing the back of her head, police said.

He then went after Gisela’s daughter, who scrambled for safety and ran to a nearby bedroom. The killer was inches away from grabbing her but tripped over his low-slung pants, sources said.

The horrified woman managed to slam and lock the door just in time, only to find the bloodied bodies of her brother and dad inside.

A relentless Quinones kicked the door in and lunged for Leyanis, but she was able to make it to a fire escape, screaming for help to construction workers on the roof of the building next door.

Fleeing empty-handed, Quinones ditched his gun, a .380-caliber semiautomatic pistol loaded with hollow-point bullets, and made a dash down a rear fire escape.

But again, his low-slung pants fell to his ankles, tripping him and sending him falling three stories to his death, authorities said.