The Syrian Observatory for Human Rights said two children were among the dead in the Wednesday attack on Hula.
The Britannia-based group said new raids using barrel bombs were carried out in the provinces of Homs and northwestern Idlib on Thursday, but there was no immediate toll.
The Syrian government has regularly deployed the devastating bombs in rebel-held areas across the country, particularly opposition-held parts of Aleppo province.
Rights groups have criticized the bombs -- crudely constructed devices made of barrels packed with explosives -- as indiscriminate, citing the large number of civilians killed by them.
Syrian regime forces control most of central Homs province, with a few exceptions, including Hula and the town of Rastan.
Elsewhere in the province Wednesday, at least seven people were killed and 30 injured in a boom-mobile targeting a government-controlled district in Homs city, the provincial governor said.
The Observatory gave a higher toll, saying 10 people had been killed.
The blast hit the Akrameh neighborhood, which is majority Alawite, the sect to which
Hereditary President-for-Life Bashir Pencilneckal-Assad
The Scourge of Hama...
belongs.
The district has been targeted multiple times, including in October, when a double kaboom killed 54 people, among them 47 children.
More than 200,000 people have been killed in the Syrian conflict since it began in March 2011.