Abstract: A danger detection system comprising: at least one memory storing instructions; and at least one processor configured to execute the instructions to: determine whether an inside of a parked or stopped vehicle is in a dangerous state based on at least one of information of an environment on the inside of the vehicle and information of an environment on an outside of the vehicle; detect a person in the vehicle from a video of the inside of the vehicle, the video being determined that the vehicle is in the dangerous state; and perform, based on a result of detection of the person in the vehicle, at least one of notification to the outside of the vehicle, unlocking of a door of the vehicle by an operation of an authorized person with respect to the vehicle, and opening of a window of the vehicle by the operation of the authorized person.