Crash investigators are interviewing passengers, people who witnessed the crash and the bus owner to find out why it crashed off Interstate 55. Investigators are still searching for answers, adding they are making progress. Gary Van Etten, NTSB said, "One or two people have given us some idea about what the driver was doing and how he was driving." NTSB investigators got that information from some of the passengers who survived the crash. They also learned the bus made two rest stops after it left Chicago Friday night around 8:30. "We've not come to any conclusions. We've not made any decision as to what happened quite yet." One of the more pressing questions is why the roof of the bus was partially ripped off during the crash. Firefighters had to finish taking the rest of the roof off to rescue a passenger. All the other passengers where thrown from the bus and found scattered, some up to thirty feet away. "We have an engineer from the bus manufacturer who will be coming down and will be looking at that exact same thing." Investigators are also focusing on the driver, his condition and the condition of the bus. They found parts of the inspection sticker on what was left of the windshield. "We have statements from the company that said it was inspected, but we need to confirm not only exactly when it was inspected, but who inspected it and their qualifications." The NTSB says its field investigation could take several more days. All the investigators involved meet every morning with an update.