Beirut - Syrian President Bashar Assad made his first appearance Thursday since a bomb killed some of his top lieutenants, looking calm and composed on state TV even as his forces turned parts of Damascus into combat zones and rebels seized two of the country's border crossings (AP).

The unprecedented attack on Assad's inner circle Wednesday, along with the government's inability to crush the rebels after five days of intense clashes in the Syrian capital, point to an unraveling of his grip on power after 16 months of violence.

"It is a war going on here, literally a war," said a 25-year-old woman in the Muhajereen neighborhood. The sounds of battle had kept her up all night and she stayed home from work because she feared random gunfire, she added.

"It reminded me of that night when the Americans shelled Baghdad nine years ago," said the woman, who spoke on condition of anonymity because she feared for her safety. "I was watching it on TV, but today I'm living a very similar situation."

Even though Assad's powerful military remains mostly loyal - suggesting a total collapse may not be imminent - the rebels appeared to be making startling gains as the civil war intensified.

Besides the fighting in Damascus, about a half-dozen rebels took over a Syrian border crossing near the Iraqi town of Qaim, said Iraqi army Brig. General Qassim al-Dulaimi. There are four major border posts with Iraq.

Rebels overtook a Syrian army outpost near the Syrian-Iraq border after clashes that killed 21 Syrian soldiers, he added.

In addition, amateur video posted online showed rebels taking over the Bab al-Hawa border crossing with Turkey, where they stomped on portraits of Assad. The Associated Press could not independently verify the video because the government bars most media from working independently in the country.

A diplomatic solution to ending the bloodshed seemed even more remote after Russia and China again vetoed a Western-backed U.N. resolution aimed at pressuring Assad's government to end the escalating conflict.

Analysts said the regime was clearly shaken by the violence in the heart of its power base of Damascus, but the next step was not clear yet.

"We should not get carried away with speculating about the impending fall of the regime," said Salman Shaikh, director of the Brookings Doha Center and an analyst on regional politics. He said the regime's forces "are still showing a certain amount of cohesiveness in battle."

Citing a network of sources on the ground, the Britain-based Syrian Observatory for Human Rights reported intense clashes in a string of neighborhoods along the southern edge of Damascus, the northeastern neighborhood of Qaboun, and in number of western suburbs.

Gunfire and booms from shelling could be heard throughout the capital, and streets in the hard-hit areas were largely empty, save for government troops or rebels.

On Thursday, many Syrians said they were not waiting around to see if the violence would end any time soon. Thousands streamed across the Syrian border into Lebanon at the Masnaa crossing point - about 25 miles (40 kilometers) from Damascus. Hundreds of private cars as well as taxis and buses ferried people across.