Security officials say more than 40 people have been killed in sectarian clashes between Sunni Islamic militants and northern rebel forces belonging to a branch of Shias in northern Yemen.
The officials say the fighting began when ultraconservative Salafis took over a Hawthi stronghold in a strategic mountainous area near the border with Saudi Arabia. The two sides battled with artillery fire, mortar shells and machine guns in the town of al-Fagga.
The officials spoke on condition of anonymity because they weren't authorized to discuss the fighting publically.
Thursday's clashes mark an expansion of the battlefield between the two rival sides, which have been concentrated in an adjacent province.