Police have cordoned off the entrance of the Billy Trail on Hayling Island this morning.
A South Central Ambulance Incident Response Unit and two paramedic officers in Land Rover Discoveries were seen entering the off road track.
An ambulance left the scene just after 1pm escorted by police officers. It is not known if the ambulance contained a casualty.
The Ambulance had to reversed down the seven mile track. An officer was seen getting into the ambulance that drove off.
Officers stood guard for most of the morning with cordon tape blocking the entrance to the trail.
Communications Manager for South Central Ambulance Service, Michelle Archer, refused to comment on the ongoing incident.