(CBS) — The Illinois National Guard remains in shock over the sudden death of a seemingly healthy officer during a fitness exam last Friday. The latest on the story from WBBM’s Regine Schlesinger.

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National guardsman Jerome Baker of Riverdale was doing his twice-a-year physical fitness exam at the Fort Custer Training Center in Michigan. Major Brad Leighton says the 29-year-old father of four young girls was in the middle of a two-mile run when he collapsed.

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“There were other soldiers that were running with him and saw that he was in distress. They called 911. The paramedics came and were transporting him to the hospital when we lost him,” said Leighton.

Major Leighton says an autopsy concludes Sgt. Baker died of natural causes but, he has no specifics. He says it’s a terrible loss for the Guard.

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“He was a great, great soldier and he will be missed,” said Leighton.