Police were called in to disperse a crowd of about 300 people after a series of fights broke out in Coventry.
West Midlands Police said they were called after the large crowd gathered outside a nightclub holding a "pre-planned" club night.
Five people were arrested in the "large-scale disorder" outside the Escape club, in Hales Street, at about 0400 BST.
The force helicopter and officers with dogs were deployed.
One police officer received minor injuries. Police said crowds left the scene by about 0500 BST.
A police investigation is under way and witnesses are being urged to come forward.
Ch Insp Kerry Blakeman said: "On arrival our officers have been greeted by a large group that have actually left the club.
"The people that have been in the club have turned their focus on my police officers.
'Pre-planned event'"As a result of that we've managed to swiftly deal with an incident that took us about 45 minutes to disperse."
He added none of the people in custody were from Coventry but were from "all over the country".
"We believe this was a pre-planned event at the club," he said.
On social networking site Twitter people were talking about a "rave" event at the club, called "One Night Stand", which had got out of hand when fighting broke out.
One user said she felt scared and wanted to go home after glasses were smashed and thrown.
Attempts by the BBC to contact the club's owners were unsuccessful.
Posted: Wed Jun 01, 2011 1:24 pm