A heavy firefight broke out on Monday between Free Syrian Army rebels and forces loyal to President Bashar Assad in a main district of the Syrian capital Damascus that is home to several security installations, witnesses said.
They said the sound of heavy machinegun fire and rocket-propelled grenades (RPGs) echoed through the heavily guarded al-Mezze district. There was no immediate word on casualties but residents said by telephone the fighting was intense.
"There is fighting near Hamada supermarket and the sound of explosions there and elsewhere in the neighborhood. Security police have blocked several side streets and the street lighting has been cut off," a housewife who lives in the area said.
The fighting in the capital came after a car bomb ripped through a residential area of Syria's second city Aleppo on Sunday, and as activists reported heavy clashes across the country between state forces and rebels fighting to overthrow Assad.
As hundreds gathered on Sunday in Damascus to mourn victims of car bombings the previous day, activists said security forces beat and arrested people at a march of more than 200 when protesters began shouting "the people want to topple the regime".
Among those arrested and beaten was Mohammed Sayyed Rassas, a leader of the National Coordinating Body for Democratic Change (NCB), an opposition group which had visited China and Russia in attempts to promote dialogue between Assad and the opposition.
Most opposition groups have rejected the NCB over its insistence on non-violence and its stance against foreign intervention.
Security forces also arrested Farzand Omar, a doctor and politician from the party "Building the Syria State," when he arrived at the Damascus airport from his hometown of Aleppo.
World powers have been unable to stop more than a year of bloodshed in Syria, a country that sits on the fault lines of several regional and ethnic conflicts. Recent army gains against rebel positions have shown no sign of quelling the violence and no negotiated settlement is in sight.
The United Nations says more than 8,000 people have been killed and humanitarian conditions are grim. The government says about 2,000 members of security forces have been killed.
In Aleppo, Syria's commercial hub, state news agency SANA said terrorists were behind the car bomb that killed two people and wounded 30 others when it exploded in a central area close to a state security office and a church.
The explosion came a day after twin blasts on Saturday killed 27 people in Damascus and wounded nearly 100 others.
Aleppo had seen less unrest than much of Syria but has recently been hit with more violence as the revolt spreads and becomes increasingly bloody.
The semi-official news channel al-Ikhbariya said security forces had been tipped off about the bomb in Aleppo and had been moving residents out of the area when it went off. It said the car had been filled with 200 kg (440 lb) of explosives.
Pictures on the SANA website showed building fronts blasted open and aid workers standing near piles of shattered masonry and bomb craters, while Syria TV showed a street corner
splattered in blood.
"The explosion came suddenly and the only thing I thought to do was fall to the ground," a girl told Syria TV, her hands and face covered in shards of glass. "Nothing remained. All the building fronts collapsed. God curse them."
No group claimed responsibility for the Aleppo attack, and an activist from the opposition's local Revolutionary Council said the government was behind the explosion.
Reports from Syria are difficult to verify as the government has restricted access to foreign journalists.
Clashes, raids across Syria
The Syrian Observatory for Human Rights said at least 19 people, including four children, were killed in rocket attacks and by gunfire during army raids and fighting with rebels across the country on Sunday.
Fighting subsided overnight in the eastern city of Deir al-Zor after army tanks shelled a Free Syrian Army hideout there in the morning, killing at least six rebels.
The insurgents retaliated by attacking roadblocks and security compounds in various districts of the city, residents and opposition activists said.
"The Free Syrian Army responded fiercely. Around 200 rebels took to the streets and hit army patrols stationed at roundabouts and schools and government buildings that have been turned into 'shabbiha' (pro-Assad militiamen) headquarters," Wael Ghaith, an opposition activist, said.
"The army has all but pulled out from the main thoroughfares by night," he added.
A statement by rebels said they had killed Major Ayham al-Hamad, a key operative in Airforce Intelligence, a secret police division that has been spearheading the crackdown on the revolt in the city.
Deir al-Zor, which lies on the Euphrates River in Syria's Sunni Muslim desert heartland, is capital of the oil-producing province of the same name. The area borders Iraq and tribes on the two sides have strong communal links.
The year-long uprising has largely unraveled an alliance between Sunni tribal chiefs and Syria's ruling Alawite minority forged by Assad's father, the late president Hafez al-Assad, who used a carrot-and-stick approach to secure the loyalty of the region.
In Raqqa, another poor Sunni Muslim tribal city on the Euphrates, troops and military Intelligence agents deployed and army snipers took to rooftops after security forces shot dead at least 20 people in the last three days, opposition activists said.
Most of the casualties were protesters killed when a large crowd tried to bring down a big statue of Assad's father, in the middle of the city, they said, adding that sporadic demonstrations continued in Raqqa on Sunday and that fighting was reported between army defectors and loyalist troops.
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