An 18-year-old died Wednesday after being thrown from a horse-drawn carriage in Central Park when the horse suddenly bolted away from its driver, according to police.

The accident occurred just before 3 p.m. in the park, police said. The teenager was riding in the carriage with three other passengers. He was taken to a hospital in critical condition and later died. The other passengers refused medical treatment at the scene.

The driver had dismounted the carriage to take a photograph of his passengers, according to Alexander Kemp, the administrative vice president of the Transport Workers Union’s local chapter, which represents carriage industry employees.

“A driver is not supposed to leave the carriage to take photos — ever,” Kemp said. “We support a full investigation.”

Kemp said the horse had been working in the park for only six weeks. He did not specify whether the horse had prior experience or training in the park environment.

Police have not announced any charges or named the driver. The investigation into the incident is ongoing. The horse’s condition was not immediately reported.

The horse-drawn carriage industry in New York City has faced periodic scrutiny over safety and animal welfare. Wednesday’s death is believed to be the first fatal passenger incident involving a Central Park carriage in recent years.