Riot police were forced to break up crowds at a teenager’s 16th birthday party after 3,000 people turned up because she left the Facebook event invitation open.
There were reports of six people hurt, three seriously, as shops were vandalised and looted, a car set on fire and street signs and lampposts were damaged in the northern Dutch town of Haren.
Up to 600 riot police were on the scene and at least 20 arrests were made, media reports said on Friday night.
As police broke up the crowds, stones, bottles, bicycles and pots of flowers were hurled at them.
The mayhem unfolded after some 30,000 people received the invitation from a girl announcing her 16th birthday party on Facebook.
Intended to be a small-scale celebration, the invitation went viral after the girl did not set the Facebook event to private and forgot to mention it was for family and friends only.
Groningen police spokeswoman Melanie Zwama told AFP: 'She posted the invitation on Facebook and sent it to friends, who then sent it to other friends and soon it spread like wildfire across the internet.'
Reports said up to 3,000 people showed up in the town of only 18,000.
Some party-goers even wore T-shirts made for the occasion. One read: 'Project Haren September 21.'
Others posed for photos outside the girl's house for the event that became known as the Project X-Party after movie Project X (2012) about three teenagers who throw a birthday party which spirals out of control as the night progresses.
Police were on high alert as Haren braced for the event for most of the week. Locals were left to clean up the streets of debris in the aftermath today.
Videos of the night posted on YouTube have already been viewed several thousands times