Two air ambulances - the Great North Air Ambulance and the Yorkshire Air Ambulance - attended the scene in remote countryside near Pickering this afternoon.
A Great North Air Ambulance spokesman said the 65-year-old man is thought to have lost consciousness following the fall, though he came round on his way to hospital.
It is not known how serious his condition is.
"The metal footbridge had totally collapsed into the river.
By the time we got there, both men had been retrieved from the water.
We think they were on a shooting party."
It is not known if they were on a shoot at the time of the incident, which took place at around 2.30pm, according to North Yorkshire Police.
North Yorkshire County Council said it was trying to find out who owned the bridge and its current condition.
Two ambulances, a rapid response vehicle and a clinical supervisor from Yorkshire Ambulance Service and two air ambulances from Yorkshire Air Ambulance and Great North Air Ambulance were dispatched to the scene."
More top news
Plans have been revealed for a new Teesside restaurant, The Fork in the Road, which says it will offer catering jobs for ex-offenders
Scientists from Newcastle University have led a breakthrough in the most common form of fatal brain tumour.
The shuttle bus service between The Friargate Hospital in Northallerton and James Cook Hospital in Middlesbrough ends today due to cuts.