The Mono-Rail Incident

You are in City of Lightning, Nibiru. You saw Joey waving at a girl as she enters a mono-rail train. When the train door was still open and the girl inside, Joey was exiting the train station and was in the park. As the train starts, you see Joey walking down the park and when the train was out of sight, a shock wave can be heard. Right after the shock wave, a crash and an explosion can be heard after. You evacuated the train station and head to the park. You saw Joey running towards the train wreck. He took something off the ground. You didn't quite see it but he just ran away. What will you do? Why is he running? How do the train crash out of a shock wave?