Security for the Rotorua Marathon is under review after a motorist forced runners into oncoming traffic in this year's event.
The marathon has been running for 48 years and this year was the first time it was held without a police escort. Instead, cyclists in high-visibility vests led the race.
The day was marred by a verbal altercation between an official cyclist and a motorist who blocked the frontrunners, forcing them into oncoming traffic.
Acting Sergeant Grant Keys said police had identified and spoken to the driver as well as witnesses but no decision had yet been made if charges would be laid. He said the event was still being analysed.
"It was a new process without the police escort leading the race and, unfortunately, this incident has occurred," Mr Keys said.