The fighting in Syria continued on Friday, as army helicopters pounded Damascus with rockets and heavy machine guns and tanks bombarded the capital from the ring road, to try to reverse relentless gains by rebels since much of President Bashar al-Assad’s entourage was assassinated.

“The regime has been rudderless for last three days. But the aerial and ground bombardment on Damascus and its suburbs shows that it has not lost the striking force and that it is re-grouping,” opposition activist Moaz al-Jahhar said told Reuters from Damascus.

The 16-month conflict has been transformed since Wednesday, when a bomb killed four members of Assad’s narrow circle of kin and lieutenants, including his powerful brother-in-law, defense minister and intelligence chief.

In the days since, Reuters noted, rebels have pushed deep into the heart of the capital and seized control of other towns. On Thursday, they captured three border crossings with Iraq and Turkey, the first time they have held sway over Syria’s frontiers.

The report said that Assad has failed to speak in public since Wednesday’s blast. A funeral was held on Friday for officials slain in the attack, but Assad did not attend and was nowhere to be seen.

The only public appearance Assad made since Wednesday was when he swore in his new Defense Minister, General Fahad Jassim al-Freij, in a ceremony aired on television by the Syrian News Agency (SANA) on Thursday.

Rebels poured into the capital Damascus at the start of the week and have since been battling government forces in what they call operation “Damascus Volcano.”

Lightly-armed rebels have been moving on foot inside residential neighborhoods and attacking security installations and roadblocks dotted across the capital.

Activists told Reuters that at least 100 people were killed in Damascus on Friday. In at least one apparent success for Assad’s forces, state TV said on Friday troops had cleared the central Damascus district of Midan of “mercenaries and terrorists.” It showed dead men in t-shirts, some covered in blood, others burned.

Opposition activists and rebel sources confirmed on Friday that they had withdrawn from that district after coming under heavy bombardment, but said they were advancing elsewhere.

Meanwhile on Friday, the UN Security Council voted unanimously to extend its monitoring mission in Syria for 30 days. Russia dropped its objections to the British proposal after it was broadened to require both government forces and rebel fighters to take steps to halt the violence.

On Thursday, Russia and China vetoed a resolution in the UN Security Council that threatened Syrian authorities with sanctions if they did not withdraw troops from towns and cities and cease using heavy weapons in a crackdown on a popular uprising against Assad.

It was the third time that Russia and China have used their veto power to block UN Security Council resolutions targeting the Syrian regime.