The Hague - Riot police went into action in a sleepy Dutch town late on Friday to contain thousands of party-goers who turned up after a teenager's birthday invite on Facebook went viral.
Dutch news agency ANP quoted a correspondent as saying the situation in Haren near the northern city of Groningen was getting out of control as police were pelted with stones, bottles, bicycles and pots of flowers by angry youths.
Describing "chaos", ANP quoted local police as saying several people had been injured, two seriously. Four arrests were made, but police said more could be expected after pictures they took were studied.
The police had been on high alert after the schoolgirl posted a message inviting friends to her 16th birthday party on Friday, but forgot to mark it as a private event, prompting more than 20 000 replies.
Public television station NOS said up to 4 000 people, the vast majority of them young, had turned up in Haren, population 18 000. Cars and doorways were damaged by objects thrown at police blocking the street where the girl lives.
Riot police made several charges to disperse the youths trying to get access to the downtown street. The birthday girl had meanwhile fled her home earlier in the day.
"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," Groningen police spokesperson Melanie Zwama told AFP.
Several websites have sprung up dedicated to the party and referring to 2012 US teen film Project X - about a suburban birthday party getting out of control after an invitation goes viral.
One site referred to Friday's party as "Project X Haren", counting down the seconds to the event and claiming 150 000 people had been invited.
It also published the party's address, adding: "By all means bring some friends!"
Previously Project X parties have run riot in different parts of the world including Germany, Australia and especially the United States, where teens wrecked an unoccupied Texas home, causing damage of up to $100 000.