BARTOW, Fla. -- For several harrowing minutes, Polk County Sheriff's Deputy Jack "Carlton" Turner III stood on Interstate 4 in the blinding fog, listening as vehicles collided around him.

Then they started to explode.

The Polk County Sheriff's Office on Friday released radio transmissions from Turner, who was the first law enforcement officer to respond to a series of crashes on the highway in central Florida that killed four people and injured 38 others Wednesday.

"My car's been hit several times," Turner tells dispatchers in a shaky voice. He positioned himself at the front of his car, trying not to get hit and listening to dozens of collisions.

Moments later, he told deputies that at least four vehicles around him were on fire. A dispatcher told him help was coming.

Polk County Sheriff Grady Judd first relayed Turner's story within hours of the crash, saying the deputy was shaken but uninjured.

"'I watched a man burn to death today,'" Judd recounted Turner saying afterward.

Turner, 26, has only been a deputy for a year and a half. He is scheduled to speak publicly about the crash Monday.

Investigators continued to work Friday to identify the dead, but some bodies were so badly charred that process has been delayed, Florida Highway Patrol Trooper Larry Coggins said.

More than 70 vehicles were involved in a series of crashes that shut down I-4 for more than 36 hours. Turner was in the middle of the most serious pileup, near a tanker that scorched several other tractor-trailers and cars.

Damage was so severe that workers were forced to repave the road.

The four people who died were involved in the major wreck -- two were riding in trucks and two were in passenger vehicles.

Troopers said dense fog contributed to the crash, and are looking into whether a brush fire that was burning out of control near the highway may have played a role. The fire was started a day earlier as a controlled burn, but got out of hand.

On Wednesday, first responders had to walk the highway and fumble around in the fog and smoke, looking for survivors.

In his first transmission, Turner tells dispatchers they need to shut down eastbound I-4 immediately. Moments later, dispatchers ask him if he's still OK.

Turner said he was.

"I can't see anything," he said. "All I hear are people constantly hitting each other."