Inspector Mark Fergus said the investigation would continue today
"A scene guard has been in place overnight at the address and police remain at the property this morning conducting a scene examination.
"Police officers will also be conducting area inquiries and speaking with nearby residents."
Ambulances responding to emergencies from the Warkworth station have been temporarily relocated while the police investigation takes place.
"St John takes very seriously the safety of its officers and has systems, alerts and supportive measures in place to ensure their security and well-being," the organisation said.
"Any abuse or assault against ambulance officers is unacceptable and will not be tolerated."
St John said it supported a parliamentary bill, titled the Protection for First Responders and Prison Officers Bill, along with the introduction of tougher penalties for those who assault emergency workers.
St John was also three years into a four-year process of phasing out shifts involving a single worker, such as the one the paramedic attacked last night was working.
Ninety-seven percent of ambulance responses were now double crewed, and double crew shifts were due to start in Warkworth next month.
Anyone with information about the incident is asked to contact Waitemata Police on 09 839 0697 or Crimestoppers anonymously on 0800 555 111.