COPENHAGEN, Denmark (AP) — Two German boys, who got buried in the sand after digging a hole in a dune in northwestern Denmark on Sunday, have died, police said Wednesday.

The boys, 9 and 12 — who were on holiday with their family from Munich — died late Tuesday, officers said. They have not been named.

They were digging a hole in a dune on the beach on Sunday when the dune collapsed, and burying them.

The boys were pulled out by firefighters and police with the help of local people, after being buried for 40 minutes. They were flown by helicopter in critical condition to the university hospital in Aarhus, Denmark's second-largest city, where they died.

Central and West Jutland Police said Wednesday they considered the case ”a tragic accident” and had no further comments.