Troopers were called to the scene north of Fort Lauderdale early Friday morning.
A witness tells Miami television station WSVN that he was driving south on the interstate and saw what looked like a body "laying across the road." He said he "couldn't react in time" and ran over it.
The man says he stopped and spoke to a motorcyclist who told him a woman had been hit. The motorcyclist drove away before police arrived. The witness says other cars hit the woman but he knows of only three people who stopped.
Authorities are investigating the crash.
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