An area monitoring system and a method of merging occurrence records in an area monitoring system whereby occurrences are monitored or recorded in external databases. The method includes receiving a first occurrence record, indicative of an event; on the basis of the applicable correlation rule, identifying a set of databases to be queried; generating a query for data according to a respective protocol; generating a correlated dataset of occurrence records from at least a subset of the set of occurrence records and the first occurrence record; and displaying to a user a visual representation of the correlated dataset of occurrence records.