stolen 2016 Trek

The incident happened at the Davis Amtrak station around 11:47 PM on Feb, 12th. The bike was left unlocked near the platform of the station while I sent a friend on the train. The thief was a guy wearing a blue hooded jacket. I saw that he was sitting near us when we were waiting for the train. He was covering his face with the hood, so I did not see his face. He took my helmet and my bike off the station and rode on my bike fast to the east side of town. We saw the incident was happening from the platform and were trying to catch him but we could not. My backpack left in the basket was also gone with the bike. It seemed to me that he had done this kind of stealing before and he knew what to do.