Examining Wikipedia, I've found the Trollhättan school stabbing with four deads, the Västerås IKEA attack with 2 deads and the Malmö school stabbing with 2 deads (both unfortunately not included in the list). The 2010 Stockholm school bombings probably don't count as the only person who has died was the terrorist himself. The map is bad in displying several terrorist attacks at the same place, e.g. Stockholm, where there at least occured the 2017 Stockholm truck attack (5 deads) and the 1975 West German embassy siege by the RAF (4 deads). Yet, it's odd that the circle size seems not to match with the number of dead victims on Wikipedia.