Officials in Utah say a 13-year-old boy has died after a tunnel he apparently dug in a sand dune at a state park collapsed with him inside.

The incident occurred just after 5:30 p.m. Saturday outside a campground area at Coral Pink Sand Dunes State Park, the State Parks Division said Monday.

A family member witnessed the collapse, and park staff members began helping digging for the boy, officials said. Deputies with the Kane County Sheriff’s Office also arrived with shovels.

Ian Spendlove, of Santa Clara, Utah, was located about 6½ feet beneath the sand about 20 minutes after the collapse, authorities said.  After responders confirmed the boy had a pulse, he was flown to a hospital in St. George and then to Salt Lake City. However, by Sunday, he had not regained brain function and was pronounced dead, the statement said.

  Coral Pink Sand Dunes State Park

Utah State Parks

“The Utah Division of State Parks extends our condolences to Ian Spendlove’s friends and family impacted by this tragedy,” officials said. “The incident remains under investigation.”

Coral Pink Sand Dunes State Park is located in southwestern Utah near the Arizona border. The uniquely colored dunes, which come from comes from Navajo sandstone,  are estimated to be between 10,000 and 15,000 years old.

Between 1985 and 2007, at least 20 children and young adults in the U.S. died in sand submersions, according to a letter from the doctors published in The New England Journal of Medicine.