The decision is based on numerous cases of overcrowding by people who were not originally invited.[14][15] In one instance, 1,600 "guests" attended the 16th birthday party for a Hamburg girl who accidentally posted the invitation for the event as public. After reports of overcrowding, more than a hundred police were deployed for crowd control. A police officer was injured and eleven participants were arrested for assault, property damage and resistance to authorities.[16] In another unexpectedly overcrowded event, 41 young people were arrested and at least 16 injured.[17]