NEW YORK — The black car hit her first, striking Natalie Guzman as she tried to cross a Queens street to buy a bag of potato chips. The 18-year-old mother of an infant managed to get to her feet and she was hit again, this time by a white car.

Four minutes later, as friends who had stopped to help her up dived for cover, a black sport utility vehicle hurtled through the 30 mph zone at an estimated 80 mph.

Miss Guzman, who could not move, was killed instantly.

None of the cars stopped. Police searched for the three hit-and-run drivers yesterday in the kind of crime that disbelieving bystanders said reinforces New Yorkers' reputation as a coldhearted lot.

The first car, traveling at about 60 to 70 mph, struck Miss Guzman as she attempted to cross the two-lane Roosevelt Avenue, which runs beneath the elevated subway tracks. Parked cars line both sides of the street.

The second car was also speeding at about 60 to 70 mph, a witness told police.

As Miss Guzman lay in the street, her friends discovered her and tried to help. They told police they believed she was still breathing. Then the SUV came barreling toward them. Miss Guzman's face was so disfigured by the wheels of the car that police asked a family member, instead of her mother, to identify her.

Eric Gioia, who represents a Queens district on the City Council, said the case recalls the death of Kitty Genovese, who was murdered on a Queens street in 1964 while 38 New Yorkers watched from their windows and did nothing to help. No one even called police. The triple hit-and-runs, he said, represent "a level of human callousness and depravity not seen since the Kitty Genovese case."

"It shocks the conscience that three separate people would be so callous as to mow someone down and just keep on going."

Miss Guzman's family believes she was intentionally killed, saying she had feared for her life since a bar fight two weeks earlier.

"The family thinks her death may have something to do with that fight," said Olimpia Urena, a neighbor who acted as a translator for Miss Guzman's mother and aunt. The family came to America from the Dominican Republic.

Police say only that they are looking for the drivers, first to determine whether the drivers knew they had hit someone.

Miss Guzman's life ended Sunday morning shortly after she left Los Primos Tournament Billiards on Roosevelt Avenue in Corona, Queens, a predominantly Hispanic neighborhood two blocks from the one-bedroom apartment she shared with her 15-month-old daughter, Laritza, and her mother, Miriam Toribio. This stretch of Roosevelt Avenue is lined with bars and social clubs.

Miss Guzman dropped out of high school after becoming pregnant, a friend says, and she had recently decided to "get her life back on track."

"She said she wanted to make her life normal, she wanted to do something with her life," Miss Urena said. "She was studying to get her [high-school diploma] and after that, she planned to go to LaGuardia Community College." Miss Guzman had a job interview to sell cosmetics lined up this week, Miss Urena said.

Miss Urena said Miss Guzman's family finds it hard to believe that three persons could run over her, and none of them would stop.

Ernesto Bruno, 56, who owns a pizza shop inside the pool hall, told the New York Times: "You get hit once, OK; twice, it's pretty unbelievable," he said. "But three times, come on. Logically, you almost can't believe it."