St John ambulance service is furious a paramedic was assaulted at the Warkworth station, north of Auckland, and says from now on people won't be able to work alone.

The sole female ambulance officer was knocked unconscious in the early hours of Monday morning after encountering an intruder, and had to spend the night in hospital.

\St John director of Operations Norma Lane told Leigh-Marama McLachlan the intruder was probably looking for drugs.