Witnesses say the 17-year-old driver sped off but he was later arrested by police.
The incident happened on Eisleben Road in Lentegeur, Mitchells Plain on Sunday afternoon.
The victim was identified only as Josephine by mense at the scene.
According to witnesses, the driver of a dark blue VW Golf had been speeding and ran a red robot at the corner of Lavender Street and Eisleben Road.
They say he hit the woman, who was crossing the road, very hard, sending her nearly 50 metres flying through the air.
They say the male driver, who sped off after the incident, was doing “well over 180km per hour” and ignored the red traffic light.
Horrified onlookers screamed as the woman and her severed limbs went flying through the air.
The driver of the Golf was tracked down to the nearby Promenade Mall where he was arrested and taken back to the scene.
Police spokesperson Captain FC van Wyk confirmed the incident and the arrest of a teen. “This office can confirm that a culpable homicide case was opened, and a 17-year-old male was arrested.
"The juvenile was brought back to the scene by an officer who found him. The female died on impact,” says Captain Van Wyk.