No group has claimed responsibility for the killing.

Gunmen shot dead an American chemistry teacher working at an international school in the Libyan city of Benghazi, medical and security sources said on Thursday.

“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 American ambassador and three other Americans.

Security sources say three soldiers were also killed in separate attacks on Thursday in Benghazi.

Two years after a NATO-backed uprising ousted 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.

(Reuters/NAN)