Police say no arrests have been made following what is understood to be a hoax callout to an alleged mass casualty event in Westport.
Hato Hone St John said it was notified of what was believed to be reports of multiple stabbings just after 8.30pm on Saturday.
It said it responded with two ambulances and four helicopters, but they were all stood down before arrival and not required.
A police spokesperson said no arrests had been made.
The spokesperson said police always erred on the side of caution and treated any reported event as real until proven otherwise.
Hato Hone St John’s head of ambulance operations Robbie Blankenstein said Spark New Zealand operated the initial call-answering platform for the 111 emergency system and most false calls were filtered out before requests for an ambulance got through.
“Emergency call handlers in Hato Hone St John’s Integrated Operations Centre treat all 111 calls seriously and any false calls we receive are reported to police. Fortunately, we don’t receive many fictitious calls for help,” he said.
It was more usual for the service to receive 111 calls that did not require an ambulance response, “for example, someone calling because they are having trouble sleeping”.
“However, when we do receive false calls for help, they can impact our response to genuinely life-threatening calls from the public as they take valuable time away from patients who urgently need our care,” Blankenstein said.
Hato Hone St John said it received on average more than 1900 calls a day, more during winter.