Egremont Market Hall birthday party hit by gatecrashers
About 400 people turned up at a 15th birthday party in Cumbria after the event was advertised on social networking sites.
Youngsters were seen throwing bottles at passing cars outside Egremont Market Hall, Cumbria Police said.
Only 150 guests had been formally invited to Saturday's event. Police took a number of people home as they were in a "drunk and incapable" state.
Insp Mark Wear warned teenagers of the dangers of promoting parties online.