“He was doing his morning exercise when gunmen just shot him. I don’t know why. He was so sweet with everyone,” said Adel al Mansouri, director at the school in Benghazi.
It was not immediately clear who was responsible for the killing.
Libyan special forces have been battling militants from Ansar al-Sharia in Benghazi. U.S. officials blame the group for attacking the U.S. consulate in the eastern city in September 2012, killing the ambassador and three other Americans.
Security sources said three soldiers were also killed in separate attacks on Thursday in Benghazi.
Two years after a NATO-backed uprising ousted veteran leader Muammar Gaddafi, Libya’s armed forces are struggling to contain militias, former fighters and Islamist militants who control parts of the vast oil-producing country.