SANAA, Yemen (AP) -- A third day of fighting in Yemen's capital pitting Shiite rebels against Sunni militiamen and army units killed at least four civilians and three fighters on Saturday, security and health officials said.
Mortar shells slammed into homes and a local hospital as the Shiite rebels, known as Hawthis, battled militias and troops allied with the Muslim Brotherhood's Islah party. The officials said three other civilians including a woman, were wounded in the shelling of the hospital.
The latest casualties raise the death toll since Thursday to 22 civilians and at least 123 fighters.
The fighting has raised fears of an all-out sectarian conflict in an impoverished country already grappling with a powerful local al-Qaida affiliate and an increasingly assertive separatist movement in the south.
Just under half the population is Shiite, but they mainly adhere to the Zaydi strain of Shiism, which is seen as very close to Sunni Islam. The two communities have long been intertwined in the political elite and military.
The Hawthis waged a six-year rebellion until 2010 against long-ruling President Ali Abdullah Saleh. The following year the country was convulsed by an Arab Spring-inspired uprising, and Saleh was eventually forced to step down in an agreement that allowed his loyalists to maintain considerable power.
In recent months the Hawthis surged from their stronghold in the north, taking a string of cities and fighting their way to the outskirts of the capital, where they have held mass demonstrations. Their critics accuse them of being a proxy of Shiite powerhouse Iran and of seeking to seize power in Yemen, claims the movement denies.
The fighting on Saturday took place on the road to the international airport and near a major military base, the state television building and on two university campuses, north and west of the capital. The fighting forced many families to flee their homes and trapped others.
The military base, around which fierce clashes flared, was home to a national army unit led under Saleh by former Maj. Gen. Ali Mohsen al-Ahmar, who fought against the Hawthi insurgency.
After Saleh's ouster, the armed forces were restructured and al-Ahmar was appointed as military adviser to the new President Abed Rabbo Mansour Hadi.
The base was to be handed over to local authorities and transformed into a public garden, but it remains under al-Ahmar's control and the Hawthis say he uses the base to recruit militias to fight them.
Shells from the fighting around the base hit the walls of Sanaa University nearby, prompting authorities to cancel classes there as well as at public and private schools.
Hawthi fighters meanwhile pressed their assault on Iman University, a bastion of Sunni hard-liners seen as a recruitment hub for militants. The school is run by cleric Abdul-Majid al-Zindani, who is considered by Washington to be a "specially designated global terrorist."
Hawthis have also attacked the state TV headquarters. An Associated Press photographer saw flames and smoke rising from the building.
Clashes erupted to the south when the army tried to prevent Hawthis from entering the city. Three rebels were killed and two troops were wounded, military officials said.
All officials spoke on condition of anonymity because they were not authorized to brief reporters.
A resident in a battle-torn road said that his family was trapped, while the ministry of health did not respond to their cry for help, as no one is able to enter the congested area.
"We cannot get out of this place, children are crying and we hear screaming in the houses," said Abdel-Qader el-Sayyad, who lives near Iman University. He said his family was trapped and rescuers could not reach them.
The United Nations has been trying to mediate a deal between Hadi and the Hawthis, who say they seek economic reforms and a new government. There has been talk for days of an imminent deal, even as both sides have built up forces in the capital.
Associated Press writer Mariam Rizk contributed to this report from Cairo.