Which atom bomb was dropped on Hiroshima, Japan by the US during the Second World War?

During the Second World War, an atom bomb was dropped on Hiroshima by the United States. The name of this atom bomb was “little boy,” which was a uranium gun-type bomb. The bombing took place on 6th August 1945 when Hiroshima was occupied by 43,000 soldiers and 280,000-290,000 civilians.