What do to if your gadgets get grabbed

I was recently in Brussels attending some meetings with members of International Consumer Research & Testing, a consortium of consumer organizations of which Consumers Union is a member. I planned to spend two days on my own after the meetings, in the medieval town of Bruges, an hour's train trip from Brussels. While on a train platform in north Brussels, I was victimized by a team of robbers who skillfully distracted me and snatched my laptop bag. Among other items, it contained my laptop