Civil rights icon and U.S. Rep. John Lewis was hospitalized Saturday night for undisclosed reasons.

Lewis' spokeswoman Brenda Jones told The Associated Press on Sunday evening that the 78-year-old Georgia congressman had been released from the hospital. All tests were completed and the doctors gave him "a clean bill of health."

She says Lewis thanks everyone "who shared their thoughts, prayers and concerns during his stay."

She did not release Lewis' condition or elaborate on when exactly he was admitted to the hospital.

Lewis had been expected at an Atlanta event Saturday evening, but did not attend.

Lewis, a Democrat, played a key role in the civil rights movement and marched with the Rev. Martin Luther King Jr. in 1965 in Selma, Alabama. He was the youngest and last survivor of the Big Six civil rights activists, led by King Jr., who engineered one of the greatest moral protests in history.

Lewis was best known for leading some 600 protesters in the 1965 Bloody Sunday march across the Edmund Pettus Bridge in Selma. At the head of the march, Lewis was knocked to the ground and beaten by Alabama state troopers. His skull was fractured. Televised images forced the country's attention on racial oppression in the South. A Democrat from Atlanta, he won his U.S. House seat in 1986.