SANAA, Yemen ( AP) — Yemeni government troops have shelled residential areas in the restive southern city of Taiz for a fourth straight day, killing three people there today, residents said.

The residents said the latest shelling came from army tanks positioned on mountains and hills around Taiz, Yemen’s second-largest city and a hotbed of opposition to longtime President Ali Abdullah Saleh.

The city has been regularly shelled by the military responding to hit- and- run attacks by armed tribesmen, and the latest bout has been going on since Tuesday.

The relentless barrage has forced scores to flee Taiz to the countryside, the residents said, speaking on condition of anonymity because they feared for their lives.

On Thursday, clashes between the army and the tribesmen in Taiz left 13 dead, according to the Defense Ministry and a security official, who spoke on condition of anonymity because he was not authorized to talk to the media.

Saleh has signed a U. S.- backed deal to step down but fighting is still raging, with near-daily protests against his rule.

The longtime ruler has been the target of months of protests in a nationwide uprising inspired by other Arab Spring revolts, and some units of his military have switched sides and joined protesters demanding his ouster,

Despite backing out on several occasions, Saleh finally signed the power transfer deal, brokered by neighboring countries, last week in the Saudi capital, Riyadh, to resolve Yemen’s crisis. It transfers power to his vice president and grants him immunity from prosecution.

However, hundreds of thousands of protesters filled city centers today in the capital Sanaa, Taiz and other cities, demanding Saleh be prosecuted for the killings during Yemen’s uprising.