A client terminal displays, on a display device, a visual feature of each of a plurality of vehicles passing through an intersection at a location where an incident occurred and map data indicating a passing direction of each of a plurality of vehicles passing through the intersection and sends, in response to a designation of any one of the plurality of vehicles, an instruction to set the designated vehicle as a tracking target vehicle to the server. When the instruction is received, a server specifies a camera of the intersection at which the tracking target vehicle is highly likely to enter next based on at least a current time and a passing direction of the tracking target vehicle at the intersection and sends camera information of the specified camera to the client terminal. When the camera information is received, the client terminal displays, on the display device, a position of a camera corresponding to the camera information to be superimposed on the map data identifiably.