Ruapuna Speedway patrons were not only treated to speeding vehicles earlier today but also a clash between two rival gangs.
A number of gang members involved in the brawl were taken to hospital to be treated for injuries which ranged from moderate to serious.
Canterbury Metro Police Detective Sergeant Brad Grainger said they do not tolerate this kind of behaviour, especially when it takes place at a public event.
"The actions of these criminal gangs are concerning and have made it unsafe for the general public," Grainger said of the incident which took place around midday.
"We would like to find out what happened and obtain evidence in relation to this offending.
"Police are interested in any information about this incident and are encouraging witnesses to come forward."
Anyone with video footage of the incident, in particular, is urged to step forward and contact police.
Christchurch Police can be reached on 03 363 7400 or anonymously via Crimestoppers on 0800 55 111.