An accident involving 28 vehicles has left at least four people dead in a town outside of Denver, Colorado.

According to The Denver Post, the accident occurred at approximately 4:50 pm on Thursday afternoon. Police say 23-year-old Rogel Lazaro Aguilera-Mederos was driving a semi when it crashed into commuters stuck in traffic. This sparked a chain reaction crash which involved at least three other semis and 24 vehicles.

Unfortunately, this caused multiple explosions and a massive fire which was spread by leaking fuel. The situation was so intense that the chief engineer for the Colorado Department of Transportation said temperatures on the highway soared to over 2,500° F (1,371° C). These high temperatures melted aluminum and Fox News reports this is complicating matters as Lakewood police spokesman Ty Countryman said “We’re still trying to identify what some of the cars even are.”

While the incident is certainly tragic, a hero has emerged in the aftermath. CNN reports Darin Barton was panhandling nearby and ran to the scene.  He reportedly managed to pull three or four people from their vehicles, possibly saving their lives.

The cause of the crash is under investigation, but authorities have said it doesn’t appear that drugs or alcohol were involved. Police has also stated the crash doesn’t appear to have been intentional.

According to CNN, Aguilera-Mederos was injured in the collision but is cooperating with investigators. It remains unclear what he has told police, but Aguilera-Mederos’ brother said the brakes on his semi failed.

Regardless of what happened, the Lakewood Police confirmed Aguilera-Mederos has been taken into custody and was arrested for “suspicion of multiple counts of vehicular homicide.” That seems like a possible rush to judgment, but Countryman told reporters, even if the semi suffered from mechanical issues, the charges should stick.