A second victim, a man, also suffered injuries in the same incident, which happened around 1 p.m. Monday in North Babylon.
Police say both victims were struck in a driveway at Commack Road and Route 231 near an AutoZone store.
After being struck, the woman became caught in the undercarriage of the van, and the driver kept going.
One eyewitness said several motorists tried to get the driver's attention as he drove away, but he either ignored them or simply could not hear them.
The woman finally became dislodged several hundred yards down the road. She was taken to an area hospital, where she died of her injuries.
The man was also taken to the hospital. He was treated for injuries described as non-life-threatening.
Suffolk County police shut down a half-mile stretch of Deer Park Avenue as they worked to piece together what happened.
Authorities elsewhere impounded a delivery truck in Ronkonkoma. They would not confirm if that vehicle was involved in the incident.
But Eyewitness News is told both the driver and the striking van have been located and are now in police custody.
Police have not yet confirmed the victim's name.