Yemen: Fears that violence could lead to civil war
At least 39 people have been killed in overnight fighting as clashes intensified in the Yemeni capital, Sanaa, doctors and officials say.
Violence escalated after a ceasefire broke down between security forces and fighters loyal to Sheikh Sadiq al-Ahmar, head of a tribal confederation.
The BBC's Lina Sinjab in Sanaa says people fear the situation could turn to civil war.