Intense fighting between the opposition and Alawite forces is raging in a half-dozen areas of the Syrian capital Damascus, the day after a bomb struck at the heart of Alawite senior command, killing at least three of Syrian bloody dictator al-Assad's top brass.
Columns of black smoke rose over Damascus on Thursday as Alawites shelled Qaboon and Barzeh, while fighting raged in al-Midan and Zahira and loud explosions were heard in Mashrou-Dumar, said the Syrian Local Coordination Committees.
Al Jazeera's Zeina Khodr, reporting from Beirut, said many people believed the latest developments had led the Syrian conflict to a turning point.
"The Damascus fighting is now in its fifth day, getting close to power base of the Syrian president", our correspondent said. "The prestige of the regime has been shattered. Losing control of Damascus [means] the regime is slowly losing its grip over the country".
Wednesday's attack, the first to target Assad's inner circle since a 16-month uprising erupted, came ahead of a Western showdown on Thursday with Russia and China over a draft UN resolution calling for sanctions.
The explosion was blamed on a bodyguard attending a gathering of security chiefs at their headquarters, prompting the White House to say Assad was "losing control" of Syria.
More than 200 people, mostly civilians, were killed on Wednesday, including 38 in Damascus, where rebels are pressing an all-out offensive, according to the Syrian Observatory for Human Rights.
Wednesday's bombing killed Assad's "Defense Minister" General Daoud Rajha, his brother-in-law Assef Shawkat and General Hassan Turkmani, head of the regime's crisis cell on the uprising, state media said.
Among those wounded were Assad's "Interior Minister" Mohammed al-Shaar and General Hisham Ikhtiyar, head of Alawite National Security.
Conflicting accounts have emerged of who carried out the attack on Wednesday and how it was perpetrated.
Syrian state media did not air any images of the blast, as in previous explosions that hit Damascus in the last two months.
Assad is reportedly to be hiding in the coastal city of Latakia, made no statement on the attack, but within hours named Major General Fahad Jassim Feraj as "defense minister", the state news agency SANA reported.
The attack was claimed by the rebel Free Syrian Army (FSA), although another group, the Brigade of Islam, also said it was responsible.
The rebels said the attack, part of Operation Damascus Volcano launched on Monday, "is the first in a series ... aimed at bringing down Assad and the pillars and symbols of the regime, whether civilian or military".
The blast came a day after the FSA - comprising army defectors and armed civilians - declared its battle to "liberate" Damascus had begun and warned the regime to "expect surprises".
White House National Security Council spokesman Tommy Vietor said Assad was "losing control," pointing to "increasing" defections and a "strengthened and more united" opposition.
Jordan's King Abdullah II warned meanwhile that his northern neighbor was on the brink of all-out civil war and that in a worst-case scenario, Syria's chemical weapons could fall into the "unfriendly" hands of al-Qaeda.
He told CNN the attack that killed core members of the Syrian regime was a "tremendous blow" to Assad but not yet the death knell for a regime that remains determined to cling to power.