CHICAGO (CBS) — Six days after he was buried alive under a sand dune in northwest Indiana, a six-year-old boy continued improving at a Chicago hospital, as doctors removed his breathing tube.

Nathan Woessner was trapped under sand for more than three hours last Friday, trapped in an air pocket on Mount Baldy at the Indiana Dunes in Michigan City, Ind.

Park rangers said, as crews were trying to free him, the hole he fell into completely collapsed, burying him under the sand. Thankfully, an air pocket kept him alive for the 3 ½ hours it took to free him from the sand dune.

He was taken to University of Chicago’s Comer Children’s Hospital, where he had been listed in critical condition until Thursday. Though his condition had been progressing for several days, it wasn’t until Thursday afternoon that he was upgraded to serious condition, after his breathing tube was removed.

Doctors said he was recovering from sedation, and was responding to commands.

Mount Baldy was closed to the public after the accident, and remained closed on Thursday, according to the National Park Service.

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