A day at the beach turned tragic when a 17-year-old boy was killed after a sand tunnel he was digging abruptly collapsed, burying him alive.

The teenager, identified as Riccardo Boni by multiple Italian media outlets, was vacationing with his family in Montalto di Castro, Italy, when the incident took place on Thursday, July 10.

The Boni family was staying at a resort in Montalto di Castro, which is about 70 miles north of Rome. The collapse occurred around 3:00 p.m. local time while he was on the beach with his father and siblings.

As reported by local outlet Corriere della Sera, Riccardo Boni and his younger siblings had moved closer to the shoreline, where they started digging a large hole that was said to be nearly five feet deep, in a more secluded part of the beach. Meanwhile, their father was nearby, dozing off under a beach umbrella. 

Children dig a hole on a beach as people walk by.  (Amy Beth Bennett/South Florida Sun Sentinel/Tribune News Service via Getty Images)

“They lost a lot of time because they couldn’t see him. When they realized he was missing they began to look for him but it was too late,” he continued. 

A witness on the beach told Corriere della Serra that “no one on the beach had heard the teenager screaming because he was completely buried within minutes.” 

A police investigation has since been opened “against persons unknown” in connection with the fatal accident, the outlet added, as authorities consider whether an autopsy will be required.

“I have spoken to colleagues, and we have never heard of anything like this happening before in Italy,” Tramontana said. “We deal with terrible situations all the time, but we can’t imagine how a game on the beach ended up this way.” 

Stepheny Price is a writer for Fox News Digital and Fox Business. She covers topics including missing persons, homicides, national crime cases, illegal immigration, and more. Story tips and ideas can be sent to stepheny.price@fox.com