A semi driver is facing homicide charges after four people were killed in a horrific, fiery crash involving 28 vehicles on a Colorado highway, officials said Friday.
Rogel Lazaro Aguilera-Mederos, 23, of Texas, is being charged with four counts of vehicular homicide, police said.
The accident occurred Thursday about 4:30 p.m. when a semitrailer traveling at a high rate of speed slammed into several stopped cars during a traffic jam, police said.
Four semis and 24 cars were involved in the crash, officials said Friday.
Joshua McCutchen said he noticed a semi barreling down the emergency lane before he saw fire, smoke and explosions.
(MORE: Man arrested in crash that injured 8 was Iraq war vet treated for PTSD: Mom)"I've never seen that many cars and that much destruction and fire," he told "Good Morning America." "It was just complete chaos."
(MORE: 30 years after 27 died in worst drunk-driving crash, survivors ask if enough has changed)Six people were taken to hospitals in unknown conditions after the crash Thursday on Interstate 70 in Lakewood, about 8 miles west of Denver.
Officials said Friday they're working to identify the victims.
Lazaro Aguilera-Mederos was not seriously injured, officials said.
There was no evidence of drugs or alcohol, and no indication he intentionally caused the crash, officials said.
(MORE: Family escapes dramatic car crash outside restaurant)Lakewood Police spokesman Ty Countryman said Lazaro Aguilera-Mederos "can't stop, doesn’t stop, and ends up colliding with several cars. And a result of that, the fire ensues."
Countryman said the accident could end up being one of the worst in the city's history.
"It is true carnage there as far as the debris, what's left of cars and trucks, along with the cargoes that were in the semis," Countryman said.
Brian Dickey, who was caught up in the accident, told Denver ABC affiliate KMGH that the back of his truck "lifted up and shoved me forward."
"I was hitting other cars. When I came to a stop, I look in my rear view mirror and all I saw was a bunch of flames" he said. "And I jumped out of the vehicle as fast as I could. There was so much fire at the time that I couldn't even really approach any of the other vehicles to see if there was any other survivors or what."
McCutchen said he saw a man who had been holding a cardboard sign and asking for money rush to the scene and pull people out of the fiery wreckage.
"He's definitely a hero -- he saved four people's lives," McCutchen said.
The overpass near the crash has been inspected and deemed safe, Colorado Department of Transportation Chief Engineer Joshua Laipply said Friday afternoon.
Westbound I-70 has reopened. The eastbound side, where the crash and fire were concentrated, still needs repairs.
All lanes are expected to reopen on Saturday morning.
ABC News' Clayton Sandell, Becky Perlow and Marilyn Heck contributed to this report.