A teenage tourist was killed when a carriage horse he was riding in got startled and bolted in Central Park on Wednesday afternoon after the operator got out to take a photo of the passengers, cops and sources said.

The idyllic trip through the greenspace took a nightmarish turn for the group – in town from India – when the coachman left his post near 71st Street and Centre Drive around 2:45 p.m.

The carriage-horse driver was at least an arm’s length from his horse to take a photo of his passengers when the animal became spooked and took off, according to sources and the Transit Workers Union.

“The horse got scared and ran super fast,” Tatianna Bresler, who works at the Tavern on the Green, told The Post.

Bresler, who called 911 as soon as she saw the crash and heard screaming, said a witness was able to slow down the runaway horse before the carriage flipped.

“The immediate reaction was just like ‘oh my god, oh my god my god’ like covering my eyes because I thought maybe someone had gotten smushed or something I couldn’t even imagine, and then I called 911,” the 20-year-old said.

The teen passenger, Romanch Mahajan, was thrown from the carriage and hit his head, the sources said.

The carriage then hit the wheel of another carriage and toppled to the ground, the TWU added.

Dramatic video from the scene shows the operator sprinting after the swiftly moving carriage, as Mahajan drops to the ground.

Mahajan was taken to Weill Cornell Medical Center, where he later died. The other two passengers did not report any injuries, the sources said.

The operator caught up to the fleeing horse slightly further south in the iconic green space, near Tavern on the Green, according to the sources.

The 7-year-old horse, named Sampson, appeared to be in stable condition and uninjured, cops and the union said.

“This is unacceptable. A driver is not supposed to leave the carriage to take photos – ever. We support a full investigation,” TWU Local 100 Administrative VP Alexander Kemp said in a statement to The Post.

“We are devastated that a passenger died after injuries suffered today in the accident in Central Park, and our thoughts and prayers are with the victim’s family,” Kemp said.

“It’s our understanding that the carriage owner has suspended the driver indefinitely and the horse will be retired from the business,” the statement continued.

The union also called out safety issues inside the park.

“Safety in the park has been a growing concern among many, and improvements are needed to be made with respect to all vehicles, including e-bicycles, delivery vehicles, pedicabs, and horse-drawn carriages,” said Kemp.

Helen David, a pedicab driver in Central Park, rushed over to the chaotic scene to find the victim’s “distraught” family.

“I saw the paramedics. I saw the ambulance. I saw everybody’s trying to, like, assist the person. You know, trying to put them on a stretcher,” David said.

Wednesday’s tragedy reignited the long-standing push by activists and some lawmakers to ban horse carriages in the Big Apple.

David, for one, thinks Mayor Zohran Mamdani and the City Council “need to really reconsider having the horses in the city of New York City because they belong in a pasture now. They gotta go,” he said.

“You know where they can be free for centuries, because this is now antiquated. It is old history now that we are still having horses and killings.”

Manhattan Councilman Christopher Marte, a fierce opponent of horse-drawn carriages who has sponsored a bill to phase them out in the Big Apple, echoed the New Yorker’s concerns.

“This was a preventable death. For years, New Yorkers have warned that horse-drawn carriages are unsafe for passengers, workers, pedestrians, parkgoers, and the horses themselves,” Marte said in a statement.

“A frightened horse in a crowded public park can become impossible to control in an instant, and today a young person lost their life.”

The horse-carriage death comes about a week after a carriage horse named Deniz collapsed and died in Central Park, likely from consuming a toxic plant.

Deniz keeled over at Strawberry Fields around 7:30 p.m. on June 9.

The horse’s death, described by onlookers as “agonizing,” occurred shortly after the animal began thrashing on the ground.

Only weeks before Deniz’s death, a coachman was injured when a spooked carriage horse charged into another horse-drawn carriage and caused it to overturn in Central Park.

“We are absolutely devastated to learn that Romanch Mahajan, the 18-year-old visitor injured in today’s carriage incident, has died. On behalf of everyone at the Central Park Conservancy, our deepest condolences go out to his family and loved ones during this unimaginable time,” the Central Park Conservancy said in a statement.

“This is the tragedy we feared when we first called last year for horse carriages to be banned from Central Park due to the risks they pose to public safety and public health. A young man came to enjoy our park and lost his life. That is not an acceptable cost of an antiquated industry operating in the middle of one of the most heavily used public spaces in America,” the conservancy said.

“We renew our call for New York City to pass Ryder’s Law, which would ban horse carriages and provide transitional job placement services for drivers. Every day horse carriages are in the park is a day the safety of New Yorkers and visitors is in jeopardy.”

Ryder’s Law, a bill to phase out horse carriages, was reintroduced to the City Council on Thursday. The law is named after a carriage horse named Ryder, who tragically collapsed while working on a hot August day in 2022.

The City Council’s health panel refused to advance Ryders Law out of committee in November, despite support from equine activists and former Mayor Eric Adams.

Edita Birnkrant, the Executive Director of the nonprofit New Yorkers for Clean, Livable, and Safe Streets, called for Mayor Zohran Mamdani to pass an executive order to shut down horse-drawn carriages in response to an uptick in incidents.

“A horse dropped dead last week. At the same time, pulling a carriage last week. They’re not well cared for. Horses are also nervous prey animals who are hardwired to bolt when frightened,” Birnkrant said.

“If you love your horse, you don’t put them in harm’s way in traffic or in a busy park. They’re also putting their passengers in harm’s way.”

Councilman Marte, who is the bill’s prime sponsor, said in the statement that the City Council must pass Ryder’s Law “before the next preventable tragedy is even worse.”

“Enough is enough. This is yet another serious and terrifying incident involving a carriage horse in Central Park, and it should make clear to everyone that delay is no longer defensible

“No minor reform will make an 1,800-pound frightened animal safe in a crowded public park,” he added.

“The Council must pass Ryder’s Law and end horse-drawn carriages before the next preventable tragedy is even worse.”