A system including a first information acquisition unit configured to acquire first information indicating a detection value of a first physical quantity in a monitored area, a second information acquisition unit configured to acquire second information indicating a detection value of a second physical quantity different from the first physical quantity, in the monitored area, and a determination unit configured to determine whether an abnormality has occurred in the monitored area, based on the detection value of the first physical quantity indicated by the first information, the detection value of the second physical quantity indicated by the second information, a first coefficient corresponding to the detection value of the first physical quantity and the detection value of the second physical quantity, and a first threshold.