New York: A 13-year-old New York boy died under tragic circumstances when he was buried under tonnes of snow while building a fort with his friend, authorities said.

Joshua Demarest, 13, died but his friend Tyler Day was found alive after being submerged for hours under tonnes of snow. The boy was playing in a snow mound on a dead end street in Greenwich as a public works truck plowed the area.

Police received a 911 call for two missing boys shortly after the truck cleared out of the area and when a search dog found a sled near the mound, crews began digging.

"I bet they moved seven tonnes of snow easily out of that pile by hand, shovels and snow rakes," Greenwich Police Chief George Bell said.

One of the boys was rushed to Saratoga Hospital after first responders pulled him from the snow, and failed to resuscitate him at the scene. He was pronounced dead soon.

Police received a 911 call for two missing boys shortly after the truck cleared out of the area and when a search dog found a sled near the mound, crews began digging

His friend was found about an hour later, miraculously conscious and alert in a pocket of air.

"You can actually see the little pocket in that huge bank that he survived in and it is nothing short of a miracle," said Bell.

It was "a true accident," he added. "That's all I can tell you. A tragedy all the way around. There was no way that anybody could have seen the kids burrowed in back there."

Department of Public Works Superintendent Leo Flynn says it would have been impossible for his workers to have seen the teens beneath the snow.

It was not immediately clear if the plow truck buried the boys or if their snow fort collapsed on them. The child who survived told investigators he heard what sounded like machinery before everything went dark.

PTI