Mary Lou Retton suffers 'scary setback' in battle against pneumonia, daughter says

Olympic Gold medalist Mary Lou Retton has suffered what's being described as a "scary setback" in her fight against a rare form of pneumonia.

Retton's daughter said that the former gymnast remains in the intensive care unit and is exhausted following that setback.

This comes after the family of the 55-year-old Retton announced she had been showing remarkable progress toward recovery.

"Though it's a lengthy journey, witnessing these improvements is incredibly heartening," said McKenna Kelley, one of Retton's four daughters. "She's beginning to respond to treatments."

Retton won five medals during the 1984 Summer Olympic Games in Los Angeles.

She was 16 when she became an icon of the U.S. Olympic movement during her gold medal-winning performance at the 1984 Summer Games. The native of Fairmont, West Virginia, also won two silver and two bronze medals at those Olympics to help bring gymnastics - a sport long dominated by eastern European powers like Romania and the Soviet Union - into the mainstream in the U.S.

The Associated Press contributed to this report.