Patients at Christchurch Hospital were treated in the corridors at the weekend as the emergency department reached capacity.
Police and St John also reported a busy Saturday night as people drank to excess before bars and clubs closed at midnight, ahead of the Easter Sunday non-trading day.
A Canterbury District Health Board spokesman said Christchurch Hospital's emergency department was "extremely busy" on Saturday night and Sunday morning.
"We had people out in corridors at times."
Some patients were diverted to the 24 Hour Surgery in Bealey Ave. Injuries were mostly alcohol-related and police had to be called "on a number of occasions" to deal with drunk patients.
A St John spokesman said it was a particularly busy night for the ambulance service.
Police were unable to say how many people had been arrested but said that it was more than the usual number for a Saturday night.
Police were processing bail applications well past noon yesterday.
A police spokesman said "pre-loaded" Cantabrians "went hard", drinking to excess before midnight.
"There were a lot of problems and a lot of disorder," he said.
"It was keeping [police] busy throughout the South Island."
- The Press
Would you consider using your retirement savings to buy a home?Related story: Retirement savings used for first home