Having consulted The Chronicle of the Popes, the Catholic Encyclopaedia, Wikipedia, and a book translated from the Italian on the Popes... No one seems to have recorded the manner of death of Pope St. Leo II.
Pope Leo I died on 461-11-10.
Pope Leo V died in 903.
Pope Leo II died on 683-06-28.
Pope Leo IV died on 855-07-17.
Pope Leo VII died on 939-07-13.
Pope Leo III died on 816-06-12.
Pope Leo IX died on April 19, 1054 at the age of 51.
Pope Leo XI died on April 27, 1605 at the age of 69.
Pope Leo XII died on February 10, 1829 at the age of 68.
Pope Leo XI was born on June 2, 1535.
Pope Leo XI was born on June 2, 1535.
Pope Leo XIII was born on March 2, 1810.