Transcript for Deadly Bus Crash on California Highway
We begin with new details about what might have played out on that highway just before that FedEx truck smashed into a tour bus carrying high school students on their way to visit a college. The images late this week, the giant ball of fire, the crash taking ten lives and leaving so many injured. Afterward, there was little left, that bus just a charred flame. The sign at their school our thoughts are with us, a message for all of those families. Bazi kanani on the new clues about that FedEx truck on fire before the crash. Reporter: Tonight investigators looking for any revenue that will explain what led to this. A bus and a truck. Reporter: The explosive crash between a FedEx tractor-trailer and a tour bus full of college-bound teens. I went outside and everything was in flames already, a lot of people screaming and begging for help. Reporter: New reports of a driver of a white sudden Dan also hit by a truck in California telling local media the truck was already on fire when it swerved across the median into oncoming traffic. That tractor-trailer slamming head-on into the tour bus, causing it to erupt into flames. Panicked students climbing through windows to escape. 18-year-old miles hill is severely burned with a broken collar bone, among several hospitalized. Absolute total terror and helplessness because I couldn't get here and he's my son and I knew he needed me. Reporter: Tonight more details about the ten people who did not survive. Among them Marissa Serrato whose twin sister was on another bus at the time and a young couple chaperoning the trip, Michael and Madison, recently engaged in Paris. They had so much love. You could just see it. We're just broken. I mean, what can you say. Reporter: Ntsb investigators say it could take months to determine the cause of the crash. They want to know not only what happened but if possible how to prevent it from happening again. David? Thank you.
This transcript has been automatically generated and may not be 100% accurate.