The girl had expected a small gathering in her hometown of Haren when she posted the invitation on Facebook, Euronews reported Saturday.
Some of the unexpected party-goers vandalized shops and looted a car before setting it on fire, and 600 police officers were sent to control the crowd.
Six people were hurt, three seriously, and 20 people were arrested.
The birthday girl fled her home hours before the crowds arrived, the report said.
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