What should you do if you see a thief on the bus?

It was 2008. It was a school holiday. I arrived in Qufu and took a bus from Qufu back to Zoucheng. At that time, there was no intercity bus from Qufu to Zoucheng, but now there is one! After I got on the bus, I sat in the middle of the car near the window and stared out the window. Not long after, a passenger came up, carrying a laptop bag in one hand and a suitcase in the other, and sat next to me. The driver asked to put the suitcase in the luggage compartment of the bus, so the passenger put the laptop bag on the seat and got off the bus with the suitcase. As soon as the passengers got off the bus, a man walked over from the back of the carriage. When he passed the seat next to me, he naturally picked up his computer bag and was about to leave when he heard a loud roar from the back of the carriage: What are you doing? The man reacted quickly enough. As soon as he let go, his computer bag fell on the seat again, and he got off the car naturally. Just like that, I watched helplessly as the thief got out of the car and drove away after stealing. By the time the owner finds out, it will be too late to call the police. After the police arrived at the scene, they took everyone to the police station to record statements. And just when we couldn't contact our classmates and were about to call the police, the police officer drove our roommate to school in a police car.