In this photo released by the Syrian official news agency SANA, smoke rises after rebels fired rockets and mortar shells that struck several parts in the capital Damascus, in Damascus, Syria, Thursday, Feb. 5, 2015 (Photo: AP)
Syrian rebels fired dozens of mortar rounds at Damascus on Thursday, killing at least five people, with government forces responding with air strikes that killed eight people.
At least 63 mortar rounds hit multiple districts of the capital, prompting the closure of Damascus University, the Syrian Observatory for Human Rights said.
A policeman was among the five dead, the Britain-based monitoring group said.
The mortar fire left usually busy parts of the capital deserted.
"Within minutes, our busy street was empty," said a resident of the Baramkeh neighbourhood, adding that the headteacher of a local school had been forced to take her students to a shelter.
The middle class district is home to several university buildings, as well as the headquarters of state news agency SANA.
In the city centre, traffic was light and many people stayed home from work for fear of the mortar fire.
SANA said four people had been killed and 60 wounded as the bombardment damaged homes and set cars ablaze.
It came two days after rebel group Jaysh al-Islam (Army of Islam) vowed heavy mortar fire on the capital in response to deadly air strikes on the besieged rebel-held town of Douma east of the capital.
Its leader Zahran Alloush said that Damascus was now considered a "military zone" and a target for the rebels.
In response to the mortar fire, government aircraft stepped up their raids on Douma and the nearby rebel-held area of Erbine.
Two children were among the eight people killed, while 100 people were wounded, the Observatory said.
The region of Eastern Ghouta, which includes Douma, is a key rebel bastion on the outskirts of Damascus, and has been under government siege for nearly two years.
Tens of thousands of civilians are affected by shortages of food and medicines.
Since mid-2012, the government has conducted frequent air raids on rebel-held areas. It is accused by human rights groups of indiscriminately killing both civilians and insurgents.
More than 200,000 people have died in the conflict, which began with anti-government protests in March 2011 and escalated into a civil war that brought jihadists streaming into the country.