The accident happened at the intersection of Lenox Ave and West 122nd Street just before 9:30 a.m.
It all started about 18 blocks to the north on 140th Street where police had stopped a blue Chrysler minivan in connection with a robbery investigation.
While investigators were questioning the driver outside the vehicle, police say one of two other people in the vehicle jumped into the driver's seat and took off.
Police said they did not chase the vehicle, but eyewitnesses said police did pursue the vehicle.
Whatever the case, the minivan sped away, southbound on Lenox Avenue. Witnesses at 122nd Street said the minivan ran the light and slammed into a silver vehicle and three pedestrians.
"I got out the way of the street sweeper and backed up and parked, so she (driver of the silver vehicle) went around me and went around the street sweeper and they hit her head on," Wayne Harris said.
"There was a man on a bicycle also. He got thrown and he was taken to the hospital," Angela Clark said.
The victims were rushed to St. Luke's and Harlem Hospitals. One of the pedestrians, the nun, was pronounced dead on arrival.
She was later identified as Sister Mary Celine Graham. The Archdiocese of New York says she was a member of the Franciscan Handmaids of Mary.
The Handmaids of Mary Convent released the following statement regarding Sister Mary Celine Graham.
"Sister Mary Celine Graham was born in Jacksonville, Florida and raised in Detroit, Michigan. Sister Mary Celine entered the convent on October 31 1948. She was a Teacher and Director of St Benedict Day Nursery before she retired in 1999, from St. Benedict Day Nursery. Before that Sister was a teacher in Wilmington, NC and High Point, NC. After her retirement from the Day Nursery, Sister Celine's main ministry was praying for priests, and our St Benedict Day Nursery Community.
We are still in shock at the loss of our Sister, a woman of strong father and courage. She was a true Franciscan Handmaid of Mary, concerned about children and the poor. We love her so much and shall miss her."
Two other pedestrians, a 58-year-old woman and a 24-year-old man, were listed in stable condition at Harlem Hospital.
Two people in the silver vehicle, a 55-year-old woman and her 15-year-old son, were taken to St. Luke's in stable condition.
Along with the two pedestrians, three people in the silver vehicle were injured.
After the crash, the two men inside the mini-van took off. Police caught one of the them, but the second man remained at large.
No names were released. The conditions of the injured were not released.