(CNN) Rogel Lazaro Aguilera-Mederos thought he was going to die and closed his eyes before his semi truck slammed into backed up traffic, sparking a massive fatal fire in Colorado, authorities said.

The semi truck hit about 28 cars and trucks along Interstate 70 on Thursday near Denver, killing at least four people and leaving several others injured, police said.

Aguilera-Mederos, 23, is being held on four counts of vehicular homicide in connection with the crash. He briefly appeared in court Saturday and a judge ordered his bond to be set at $400,000. Formal charges have not yet been filed, pending the results of the investigation.

Rogel Lazaro Aguilera-Mederos (left) appeared in court Saturday.

Investigators say Aguilera-Mederos told them he was driving at 85 mph when the brakes failed. He tried to pull over to the shoulder to avoid stopped traffic but another semi had stopped there, an arrest affidavit shows.

"Rogel said he thought he was going to die so he closed his eyes before hitting the stopped traffic," the document states.

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