A 28-year-old rider died after the horse she was on threw her after being spooked by the wind.
The woman was riding along Sywell Road in Overstone with a friend who was also riding a horse when the tragedy unfolded at about 11am on Saturday.
The victim, named by police as Janette Smith, of Somerford Road, Wellingborough, was prounounced dead at the scene as officers who attended said they had never witnessed a death caused in this manner.
The horse is believed to be owned by the victim and was taken to nearby Whistlefield Stables, in Overstone Park.
The owner of the stables, Roland Smith, said: “I knew the rider a bit as she would visit the stables from time to time.
“It’s just a really tragic story, a lot of the people around here are stunned.
“I’ve heard from the other rider that both the horses were suddenly spooked, and she doesn’t know why.
“The other rider got her horse under control but the victim’s horse bolted and bucked, throwing her off. Her helmet came off as she was thrown off the horse.
“She always struck me as a very safety-conscious person – she always had body protection on, correct clothing and a high visibility jacket. Horses can be very dangerous and unpredictable at times.”
Officers closed the road for more than an hour from 11.10am.
Police are treating the incident as a tragic accident and have said no vehicles were involved.
Inspector Daemon Johnson, of Northamptonshire Police, said: “A 28-year-old was riding a horse down Sywell Road when the horse became distressed by the wind.
“She was thrown from the horse, landing on the road, and suffered fatal head injuries.
“Emergency services were at the scene, but due to serious head injuries, she died at the scene.
“It’s a very rare incident. We attend incidents where people have been thrown off horses, but none have resulted in a tragic death like this.
“No vehicles were involved and we are treating it as a tragic accident.”
Witnesses to this incident, or anyone with information about it, should contact our Drivewatch Hotline on 0800 174615.