UPDATED 8:31pm: A female ambulance officer has been left shaken after being ambushed for drugs while heading to a call out in Hamilton.

While on the way to a call out last night, she was waved down by a man on Cameron Road seeking help for another man lying on the ground.

When she was helping him, two other men came along, forced her back into the ambulance and demanded drugs.

While the group searched the ambulance, the officer was able to call for help and escape the situation.

St John regional manager Eddie Jackson says they take the safety of their officers and patients very seriously.

"And to have such a premeditated act, to interrupt both the response of a vehicle but then to act in such a way, I just find absolutely despicable."

He says the ambulance officer is now on leave and receiving support from St John.

Detective Senior Sergeant Ross Patterson says the offenders showed no respect to the service ambulance officers provide.

Police want to hear from anyone who may have seen or heard any disturbances in the Hamilton suburb last night.

Detective Patterson says forensic examinations will take place today.

"We're trying to establish at this stage whether there's anything actually missing from the ambulance, so an examination of the truck is being conducted today."

Photo: Supplied