A police spokesman said officers responded to the collision at the intersection of Frederick St and Cumberland St (State Highway 1), in north Dunedin about 9.20am yesterday.
A lane was blocked until the crash was cleared and inquires were ongoing, the spokesman said.
A witness said the ambulance had received damage to its front.
St John district operations manager for Southland-Otago Pauline Buchanan said the ambulance crew had been responding to an incident and was operating its flashing lights and sirens.
After the collision, another vehicle was dispatched to respond to the initial incident.
Three ambulance officers were assessed at the scene by two other ambulance crews that responded to the incident.
They were uninjured, but another patient at the scene received moderate injuries.