(CNN) -- Florida authorities had reopened a section of Interstate 75 barely half an hour before a pileup on the smoke-shrouded highway that killed 10 people over the weekend, a state Highway Patrol spokesman said Monday.
The interstate was closed for about three hours early Sunday, after a pair of late-Saturday crashes on I-75 and nearby U.S. 441, just south of Gainesville, Lt. Patrick Riordan told reporters Monday afternoon. Troopers, state Department of Transportation officials and local sheriff's deputies reopened the road after determining that conditions were improving, he said.
Riordan said the interstate reopened at 3:26 a.m. Thirty-three minutes later, callers began to report chain-reaction crashes in both the north and southbound lanes of I-75.
"I can't see anything. It's so dense -- the fog is so dense -- and we just hit a guardrail, and I think there was another accident behind us," the first caller told an Alachua County sheriff's dispatcher.
The bangs of several subsequent crashes could be heard in the background of nearly 13 minutes of 911 recordings released Monday. The voices on the calls reflected the fear and confusion of the predawn scene.
"Here comes another one. He's coming too fast. Here comes another one. Oh, yep -- see, there he goes ... that one was a bad one," one woman told dispatchers.
In the end, at least 12 passenger cars and seven semis were involved in the crashes. Subsequent fires burned three of the 10 dead "to a point where positive ID has been a hurdle for us," Riordan said. He said state troopers "did their due diligence" before reopening the road, but, "Sometime after the roadway was reopened, the conditions changed quickly."
In the wake of the crashes, he said the Highway Patrol would "review this situation and determine if our process needs to be changed."
"Certainly, we're open to that," he said. But he added, "All drivers need to be prepared to change their driving based on the roadway conditions."
Florida Gov. Rick Scott said he has asked the state Department of Law Enforcement to investigate the circumstances behind the crash, promising to make "any and all resources" available for the investigation.
"We will also fully cooperate with any federal investigation which may occur," Scott said in a written statement. "During this tragic time, our thoughts and prayers should be with the victims and their families."
Steven Camps, one of the survivors, told CNN that all he could hear after the crashes stopped was the sound of crying. The air, heavy with smoke, shone red from vehicle fires.
"It was just so crazy," he said. "We were just sitting in the car, and all of this came out of nowhere."
Camps said he was returning to Gainesville from Micanopy, about 12 miles away, with a friend early Sunday when traffic came to a stop on the interstate in what looked like heavy fog. He was a passenger in the car, and said they were talking to a man in a stopped car in the next lane about the low visibility when they began hearing crashes from behind them.
The car next to them "literally almost went under (a) semi-truck," he said. "We saw that guy die after talking to him before we could even react."
He said the car he was riding in was then struck twice. He was not hurt badly, but his friend could "barely even move," he said. Camps pulled his friend from their car, which wound up wedged between two tractor-trailers, to the median, where they prayed that another car would not leave the roadway and hit them.
"As it was happening on the northbound side, it was happening on the southbound side as well," he said. "There was nowhere to go. It was just cars hitting cars and cars."
The Miami-to-Michigan interstate was open again Monday, but the National Weather Services said patches of smoke were likely to hang over the area into Tuesday.
The smoke is from a brush fire at the nearby Paynes Prairie Preserve State Park. The blaze, called the Boardwalk Fire, was 100% contained but was not considered controlled, Ludie Bond, wildfire mitigation specialist for the Gainesville area, said Monday.
While fire lines were in place, active smoke could linger for weeks to months, she said.
Camps said he received stitches in his leg and was released from a hospital. He said his friend was still hospitalized but may be released soon. He said he was "blessed" -- "If you saw the car, you'd be like, 'How did you live?' "
Shands Hospital at the University of Florida received a total of 18 patients, six with serious injuries, said Dr. Timothy Flynn, the hospital's chief medical officer. Eight of the remaining 12 were treated and released, he said.
The Florida Highway Patrol said Monday that a total of 21 people were taken to hospitals.
CNN's Vivian Kuo, Rich Porter, Jacqui Jeras and Darrell Calhoun contributed to this report.