A method for detecting a scan irregularity in scanning of one or more items by a user, during check-out process at a retail store, the method comprising: receiving a video stream of a scanning zone in real-time from at least one video camera, wherein the scanning zone is a region in a field of view of a scanner of the retail store; processing each image frame of the video stream to detect one or more visual scan intervals in one or more image frames, wherein the visual scan interval is a time interval during which an item is identified in the scanning zone for scanning by the scanner; processing each detected visual scan interval to determine whether the detected visual scan interval is valid, wherein said processing is based on a set of pre-defined rules and wherein a processed visual scan interval includes a scan action, wherein the scan action is a user action performed for scanning an item; detecting a scan irregularity in the check-out process for each detected valid visual scan interval and providing an alert regarding the scan irregularity at a user computing device wherein detecting the scan irregularity comprises comparing the item associated with the valid visual scan interval with a list of scanned items generated by the scanner during the time interval and wherein if the item is absent in the list of scanned items, detecting a scan irregularity in the check-out process, characterized in that a first pre-defined rule of the set of predefined rules comprises validating a detected visual scan interval based on computation of a glass motion coverage in one or more corresponding image frames, wherein the glass motion coverage is a ratio between a number of frames depicting a glass area of the scanning zone and a number of frames having a foreground other than the glass area, in the scanning zone, wherein the glass area is that area in the scanning zone that contains a glass that covers the scanner. receiving a video stream of a scanning zone in real-time from at least one video camera, wherein the scanning zone is a region in a field of view of a scanner of the retail store; processing each image frame of the video stream to detect one or more visual scan intervals in one or more image frames, wherein the visual scan interval is a time interval during which an item is identified in the scanning zone for scanning by the scanner; processing each detected visual scan interval to determine whether the detected visual scan interval is valid, wherein said processing is based on a set of pre-defined rules and wherein a processed visual scan interval includes a scan action, wherein the scan action is a user action performed for scanning an item; detecting a scan irregularity in the check-out process for each detected valid visual scan interval and providing an alert regarding the scan irregularity at a user computing device wherein detecting the scan irregularity comprises comparing the item associated with the valid visual scan interval with a list of scanned items generated by the scanner during the time interval and wherein if the item is absent in the list of scanned items, detecting a scan irregularity in the check-out process, characterized in that a first pre-defined rule of the set of predefined rules comprises validating a detected visual scan interval based on computation of a glass motion coverage in one or more corresponding image frames, wherein the glass motion coverage is a ratio between a number of frames depicting a glass area of the scanning zone and a number of frames having a foreground other than the glass area, in the scanning zone, wherein the glass area is that area in the scanning zone that contains a glass that covers the scanner.