Arab Spring unrest: 49 dead in Yemen, Syria .

Shelling by Yemen's Republican Guard and pre-dawn street battles between government forces and rival tribal fighters killed at least 41 people in the capital Wednesday.

Meanwhile in Syria, at least eight people, including an 11-year-old girl, were killed over two days when Syrian troops shelled a town in the country's south, a human rights activist said.

Fighting in Yemen raged until 5 a.m. local time Wednesday (10 p.m. ET Tuesday). Witnesses said Presidential Guard units shelled the headquarters of an army brigade responsible for guarding sensitive government institutions.

There were growing signs of disarray in beleaguered President Ali Abdullah Saleh's military. Army officers who have defected to the opposition say the government suspected the brigade commander, Brigadier-General Mohammed Khalil, was about to join forces with the movement to oust Saleh.

Video: Yemen faces 'all-out civil war'

Opposition army officers, speaking on condition of anonymity in line with army rules, said Khalil was neutral and without political affiliation but had apparently angered Saleh.

The 41 dead included combatants from both sides of the conflict, said the medical officials, who spoke on condition of anonymity for fear of reprisals.

The fighting engulfed the Hassaba neighborhood that contains the family compound of influential opposition tribal leader Sheik Sadeq al-Ahmar, and to the north of that district where Republican Guard units protect Saleh's former residence.

The units, led by one of Saleh's sons, and special forces wearing uniforms of government security troops attacked but failed to recapture the Hassaba administrative building from tribal gunmen.

Water, electricity cut off
On Tuesday, Saleh imposed collective punishment on the Hassaba neighborhood by cutting water supplies and electricity.

A resident who lives close to the fighting and would only give his first name, Zaher, said columns of smoke and fire billowed from Khalil's brigade headquarters and explosions could be heard.

Yemen is on the brink of financial ruin, with about a third of its 23 million people facing chronic hunger.