In Damascus, two mortar shells struck the upscale neighborhood of Mazzeh during the morning rush hour Thursday. An AP reporter said one of the shells set fire to a six-floor apartment in a residential building, seriously injuring one woman. The second mortar struck and damaged the first floor in a building across the street.
Downtown Damascus -- the seat of Assad's power -- has seen scores of car bombs and mortar attacks in recent months. Mazzeh, home to a number of foreign embassies as well as homes of wealth Syrians, including one exclusive compound housing members of the regime, has been targeted several times in the past few days.
"This is a residential area and there are no military bases here. So why are they targeting civilians?" said Nizar Hamdi, a 38-year-old owner of a computer center.
Syrian TV showed a girl in school uniform who said the mortar fell as she was preparing herself to go out.
"It was terrifying, I couldn't go to school. People were screaming," she said.
The state-run SANA news agency also reported that a car bomb exploded in the Massaken Barzeh district of the capital, wounding another person.
The reports blamed "terrorists" for the attacks, a term the government uses for opposition fighters.
Meanwhile, the military pounded opposition strongholds in the outskirts, activists said. In videos that were posted online by activists Thursday, mortar rounds and artillery shells can be heard landing in the suburb of Daraya. Plumes of black smoke are seen rising from behind rows of houses in a residential area and a fire engulfs a one of the buildings that was hit.
With a population of about 200,000, Daraya is part of Rural Damascus, a province that includes the capital's suburbs and farmland. It has been a stronghold of support for the rebels fighting the government since the start of the uprising, posing a particularly grave threat to Assad's seat of power.
In August, troops backed by tanks stormed the town after several days of siege, with hundreds reportedly killed.
To the north, near the border with Turkey, fighting broke out in the city of Ras al-Ayn on the Syrian side of the border between Kurdish and Arab rebel factions, according to an official at the mayor's office in the nearby Turkish town of Ceylanpinar. He said two wounded rebels were brought over to Turkey for treatment, but he did not say to which faction they belonged. The official spoke on condition of anonymity in line with government rules.
Kurdish and Arab groups cooperated to oust Syrian regime forces from the ethnically mixed area earlier this month, but they have since frequently clashed over control of the city.
The Syrian Observatory for Human Rights, which relies on reports from the ground, confirmed the infighting.
Syria's conflict erupted in March 2011 with an uprising against Assad's regime, inspired by other Arab Spring revolts. The crisis has since morphed into a civil war, with scores of rebel groups across the country fighting government troops. More than 40,000 people have been killed in the 20 months of unrest, according to activists.