In the case of such events, all perimeters need to be properly monitored to ensure people without tickets do not gain access, and entrances and exits need monitoring to ensure the process goes smoothly. With large crowds, thefts and muggings are common occurrences, and security needs to ensure the safety of visitors. In addition, physical security can be an issue, as violence has been known to break out at these types of events, experts in the field have argued.