A volunteer firefighter who was kicked in the head by a drunken party goer says he has no idea what sparked a mob attack at a teenage birthday party in the small Marlborough town of Havelock early this morning.



Three people have been arrested and charged over the incident.



The crew of four volunteers were called to what they thought was a car crash on Mahakipawa Road about 1.20am. But when they arrived, they were confronted with an "agitated and aggressive" group of about 20 people milling around a car.



The firefighter, who asked not to be named, said he was kicked around the head and another crew member was hit in the face.



"I struggled with one guy then another guy went down on the ground with the fellow, then another guy came in and kicked me a few times."



Both received grazes and bruises around their face.



The man said he had no idea what provoked the mob.



"They were just extremely agitated and aggressive as soon as we turned up."



He had been a volunteer firefighter for three years and others up to five years, and none of them had never experienced anything like it.



"We were just all shocked, it was just something none of us had ever come across before, not in our town." He said Havelock was a small town of about 600 people, but he didn't recognise anyone at the party.



The man said he tried to keep things calm, but the crew quickly had to flee, leaving their gear behind.



"I lost my helmet and that, and we just left everything... jumped in the truck, locked the doors and took off down the road until the police arrived."



"It all happened real quick, it was quite surreal."



He said the local policeman arrived soon after but was also outnumbered until police back-up arrived from Blenheim, 63 kilometres away. Blenheim police arrested three people, who will be appearing in Blenheim District Court on October 26, facing various charges.



More serious charges may be laid, Senior Sergeant Peter Payne said.



Mr Payne said said although the party was for an 18-year-old, it was a "unruly and violent" group of adults "grossly affected by alcohol" that allegedly caused the problem.



"On this occasion it was not the young people that were causing problems but the adults at the party, 30-40 year old people."



There was no crash, he said.



Police were "shocked and disappointed" that people would stoop to assaulting emergency services who were trying to help people who could have been seriously injured in the reported crash.



Neither police nor the fire service would offer any further comment until Monday.