"St John takes very seriously the safety of its officers as well as the security of its patients and to have such a premeditated act to interrupt both the response of the vehicle and then to act in such a way I find absolutely despicable," he said.
"I'm at a bit of a loss for words to express how I feel about this particular action."
Mr Jackson said security procedures were being reviewed, and he did not discount the possibility of cameras being installed in ambulances as a result.
"It's not something that's being routinely considered but it would certainly be on the agenda to see whether that's viable."
Detective Inspector Chris Page said police were seeking the public's help to find four dark-skinned males aged about 18 or 19. The group were after illegal drugs that are not stocked in ambulances.
"These offenders have shown absolutely no respect for the service that St John provides for this community. How would they feel if that was one of their family who this ambulance was on its way to?"
Karl Andersen, the general secretary of First Union, which represents more than 1000 ambulance staff, said single-staffed ambulances were a problem that the union had been campaigning against.
He said the Government should be giving more money to St John so the ambulances could carry two crew.