Armed clashes that began on 31 May are continuing in and around Sanaa, pushing Yemen closer to civil war. So far, at least 41 people have been killed.
The violence escalated after a ceasefire broke down between security forces and fighters loyal to Sheikh Sadiq al-Ahmar, head of a tribal group. Analysts are warning that the situation could erupt into a full out war.
Meanwhile, presidential guard units shelled the headquarters of an army brigade responsible for guarding sensitive government institutions.
Army officers, who defected to the opposition, say the government suspected the brigade commander was about to join forces with the movement to oust President Ali Abdullah Saleh, who is still refusing to step down.