A wrong-way crash along the Turnpike is under investigation by the Florida Highway Patrol in Martin County.
Wednesday's accident involved a van going southbound in the northbound lanes and colliding with a semi, just south of the Martin Downs exit.
Residents of the nearby Hammock Creek community tell CBS 12 News that they heard the loud crash.
"I was just working in the house and I heard what sounded like a sonic boom."
"I was inside and so I was holding the newborn and my wife heard a huge loud bang and so did I. I came outside to see what was going on. When out there to check the streets, see the damage. It was unbelievable."
Video of the scene showed the semi on its side in a heap of mangled metal, along with the front of what appeared to be the van completely crushed. Debris was strewn across both lanes.
The van's driver was thrown from the vehicle and is in critical condition.
The northbound Turnpike lanes were shutdown for at least two hours.
It was the third wrong-way crash on a major roadway in the area since late March.