BEIRUT -- Bullets and shrapnel shells smashed into homes in the Syrian capital of Damascus overnight as troops battled rebels who took their fight against President Bashar Assad to the center of his power.
For nearly 12 hours of fighting that lasted into the early hours Saturday, rebels armed mainly with assault rifles battled Syrian forces in the heaviest fighting in the Assad stronghold since the 15-month-old uprising began.
U.N. observers said rebels fired a rocket-propelled grenade at the local power plant, damaging parts of it and reducing six buses to charred shells, according to video the observers took of the scene.
Syrian forces showed the regime's willingness to unleash such firepower in the capital: At least three tank shells slammed into residential areas in the central Damascus neighborhood of Qaboun, an activist said.
Intense exchanges of assault-rifle fire marked the clash, according to residents and amateur video posted online.
At least 52 civilians were killed nationwide outside Damascus on Saturday, according to the Syrian Observatory for Human Rights, a Britain-based activist group.
Among them were 20 people who died in early-morning shelling in the southern city of Daraa, where the uprising against Mr. Assad began in March, 2011. They included nine women and children.
In the coastal region of Latakia, six children were among 10 killed by a shell that exploded in a house where they took cover during fierce fighting, the group said. The group's figures could not be independently confirmed.
The Damascus violence was a dramatic shift; the capital has been relatively quiet compared with other Syrian cities throughout the uprising. Damascus and the northern city of Aleppo, the country's largest, are under the firm grip of security forces.
The rebels' brazenness in the Damascus districts underscored deep-seated Sunni anger against the regime, with residents risking their safety -- and potentially their lives -- to shelter the fighters.
Residents burned tires to block the advance of Syrian troops, sending plumes of smoke into the air, amateur video showed.
Urban Sunni Syrians had once mostly stayed at arm's length from their mostly rural compatriots leading the uprising, fearing the instability that their leaderless, chaotic movement would bring.
But it appears that a series of massacres of mainly Sunni peasants over the past few weeks have tipped some of their urban brethren in favor of the uprising.
One rebel supporter in Qaboun said the recent mass killings made people see rebel fighters more as protectors against Mr. Assad's forces.
Meanwhile, the main Syrian opposition umbrella group, the Syrian National Council, elected Kurdish activist Abdelbaset Sieda as its leader at a meeting in Istanbul today, a council statement said. He succeeds Burhan Ghalioun, a liberal opposition figure who had presided over the council since it was formed in August of last year.