There will be no more parties at the Flannery house in Warilla after 300 uninvited guests pushed down a steel fence on Saturday night to gain access to the celebrations.Lake Illawarra police were forced to shut down the party because of the gatecrashers' potentially volatile behaviour, which resulted in rocks being thrown at police and a young boy being hit by a car.Mother of two Sharon Flannery, who hosted the Helen St party for her son Shaun's 18th birthday, warned young people if they continued to post invitations on social networking sites, it would be the death knell for house parties. Mrs Flannery only learned about 6pm on Saturday that some of Shaun's friends had posted details of the party on MySpace and Facebook.As partygoers started trailing into the backyard, Mrs Flannery grew concerned there would be more than the anticipated 100 friends, so her husband Mick reported the situation to Warilla police.About 11pm, six police cars arrived and officers told Mrs Flannery to turn off the music and shut the party down.Police closed off Helen St and spent the next two hours herding the gatecrashers from the area.During the fray a 14-year-old from Warilla was struck by a car. He sustained cuts and bruises and was treated at Wollongong Hospital. At Warilla Surf Club, youths threw rocks at police and the rear window of a police sedan was smashed, while another vehicle was damaged.Lake Illawarra Insp Steve Johnson said 10 people were detained and were later released pending further inquiries.Mrs Flannery denied there were any similarities between the party and Melbourne teen Corey Worthington's infamous house party in January last year.Corey's parents were on holiday when an estimated 500 people descended on his family's home after hearing about the party on MySpace. The night ended in a $20,000 repair bill and riots that were subdued by police helicopters and the police dog squad."Most of the people were well behaved - it was the gatecrashers that caused the problem," Mrs Flannery said.Lake Illawarra police Chief Inspector Danny Sharkey said they were increasingly being called to parties that had been promoted on social-networking sites, which he called the "Corey phenomenon".