Regime forces Wednesday pounded rebel bastion Rastan, in central Syria, at an average rate of "one shell a minute," said a monitoring group, adding that six people were killed across the country.
Besieged by regime forces, Rastan is home to a large number of rebel fighters, according to opposition sources.
Most of Rastan's residents have fled after months of fighting, but regime forces have been unable to regain control of the town. On May 14, 23 regular troops were killed in fighting during a failed assault.
In the southern province of Daraa, one civilian was shot dead near an army checkpoint at Inkhel, said the Syrian Observatory for Human Rights.
In nearby Sheikh Meskin, several youths were arrested, according to the Britain-based watchdog.
Another civilian was killed by regime forces in the northern city of Aleppo, while in Qusayr in the central Homs province, a third civilian was shot dead by a sniper, the monitoring group added.
In the suburbs of Damascus, a blast killed three people on the international airport road, the Observatory said, without specifying whether they were civilians or soldiers.
A loud explosion was heard in the capital Damascus, the Observatory said, without providing any further details on the blast.
Other blasts were heard in several Syrian provinces during the night, including in Harasta and Douma, two suburbs of the capital that have seen fierce fighting between regime and rebel forces in the past few days.
A total of 26 people, including 14 civilians and 12 soldiers, were killed in violence on Tuesday, the Observatory said.
Fighting has grown increasingly violent around Damascus, Aleppo and northwest Idlib, despite the presence of some 270 UN truce monitors on the ground.
More than 12,000 people have been killed in Syria since a revolt broke out in March last year, prompting the regime to launch a fierce crackdown on dissent.