St John Wakatipu station manager Craig Downing says lives could have been put at risk after someone slashed the tyres of an ambulance overnight on Sunday.
"It's extremely concerning and distressing to us because it is an emergency vehicle that is available to respond," he said.
Mr Downing found the tyres slashed as he went to de-ice the vehicle shortly before 8am yesterday morning.
Queenstown police say inquiries are continuing.
