Video footage has emerged claimed to be from a boy racer gathering on State Highway 2 north of Napier.
The 100-car gathering on a section of State Highway 2 caused "significant damage" to the highway and has already led to four arrests.
The gathering, labelled "anti-social" and "dangerous" by police, occurred on October 16, near Tangoio, north of Napier.
The video shows a police car travelling slowly on the highway, and someone yells out "let it through".
Cars are shown doing burnouts, down to the rims of tyres.
Police said a spectator was injured, a police car was set upon and the highway was left scrawled with tyre marks during the night event.
Social media video shows large crowds of boy racers doing skids.
Hawke's Bay Road Policing Acting Sergeant Matt Burt said police had been "significantly outnumbered".
Burt said they'd had to put diversions in place while the event was occurring, inconveniencing motorists who were forced to take rural back roads to avoid the road.
"One police patrol vehicle was damaged when it was set upon by several of the group after being caught up in the event attempting to get through to warn motorists approaching from the north. Thankfully no police staff were injured."
So far police have seized four vehicles and made four arrests, and say more could be to come.