DAMASCUS, Syria -- Two suicide car bombers struck Syria's army command headquarters on Wednesday, killing four guards and engulfing a key symbol of President Bashar Assad's embattled regime in flames, state-run media and witnesses said.

The twin blasts were followed by several hours of gun battles between rebel fighters and regime forces in downtown Damascus. A reporter for an Iranian TV channel also was killed by gunfire near the clashes, and a correspondent for another Iranian station was wounded.

The brazen rebel attacks in the heart of the Syrian capital highlighted their determination to bring down Assad as the country's civil war intensifies.

Syria's unrest began in March 2011 when protests calling for political change met a violent government crackdown. Many in the opposition have since taken up arms as the conflict morphed into a civil war that activists say has killed nearly 30,000 people. Over the past few months, the rebels have increasingly targeted security sites and symbols of regime power in a bid to turn the tide in the fighting.

Rebels from the Free Syrian Army claimed responsibility for Wednesday's bombings.

The blasts went off about 10 minutes apart, starting around 7 a.m., near the landmark Omayyad Square. They were heard several miles (kilometers) away.

Syrian state TV aired what it said was security camera footage of the blasts. In the first, a white van is driving on the road outside the military headquarters, then veers to the right and explodes. The second blast goes off inside the compound, with flames rising from behind trees.

Later, the army command building is seen engulfed in flames that sent huge columns of thick black smoke over Damascus for several hours.

The explosions shattered the windows of the Dama Rose hotel and other nearby buildings, as well as windshields of parked cars. Footage by the Syrian TV channel Ikhbariya, also state-run, showed heavy damage inside the compound, with glass shards scattered across the floor and broken ceiling tiles.

The blasts caused fear among residents of a nearby upscale district, which has largely been sheltered from the violence that plagues other parts of the city.

"What if a random bullet killed one of my kids?" Nada, a 42-year-old mother of three who only gave her first name out of security concerns, said, crying over the telephone. The windows of her apartment were shattered and her furniture was damaged. "I only care about my children and I'm afraid of the gunfire," she added.

Gaith, 63, a retired civil servant who also just gave one name for the same reason, said he rushed to lock the gate of his building to keep rebels from hiding inside. "I don't want my place to collapse on my head," he said.

Witnesses said the explosions were followed by heavy gunfire that stretched on for hours at the Omayyad Square and around the military compound.

One witness who managed to get close to the area, which was cordoned off, saw panicked soldiers shooting in the air randomly as they ran.

The British-based Syrian Observatory for Human Rights, which relies on a network of activists on the ground, said heavy clashes were taking place inside the compound of the army command, adding that both sides had suffered casualties.