Gray said the police had blocked off the Te Huinga trail which leads there.
Luka Ellis came for a mountain bike ride today to get out of the house and said the Te Huinga Mini Downhill track was taped off so he turned around and came back.
Ellis said saw the tape at the top end of the track, which loops on to Nursery Rd, and there was a police officer at the bottom end of the track.
A group of people running said they saw police cars at the bottom of the track on Nursery Rd.
A reporter at the scene said a fire truck was seen driving up the gravel of Nursery Rd.
Mountain biker Garth Weinberg said the Mini Downhill track was well maintained and well used but there were "a few surprises".
Mountain Bike Rotorua owner Tak Mutu said they, like everyone else, were waiting to hear what police said had happened.
"Something unfortunate has happened in the forest, whether it was an accident or not, only time will tell."
Mutu said the trail was a standard trail built in the past few years.