Investigations into the incident have been carried out through the night and will continue today.
"Police are as concerned as the public about the number of aggravated robberies in Canterbury of late and is working tirelessly to investigate these incidents and hold the offenders to account," said Detective Inspector Darryl Sweeney.
"We encourage bar owners to ensure they do their banking daily and remain especially vigilant around closing time."
Canterbury Police have been visiting all the licensed establishments in the region to offer prevention advice.
Any bar or hotel owner who has concerns and would like to talk with Police should call Christchurch Police on (03) 363 7400.