An American language teacher has been shot dead in his car in Yemen.

Security officials say two gunmen on a motorcycle opened fire on the teacher Sunday in the city of Taez.

The victim has not been identified and no one has yet claimed responsibility for the attack.

The killing comes three days after a Swiss language teacher was kidnapped in Yemen's port town of Hodeida. It is not clear who abducted the woman, and there is no apparent motive.

Yemen has fallen into chaos since last year when protests forced then president Ali Abdullah Saleh to flee the country. Al-Qaida militants have taken advantage of the situation and seized control of a number of towns.