The Britain-based Syrian Observatory for Human Rights said the attack targeted a building used by pro-government militiamen in the town of Salamiyah. It said civilians were among the dead.
Syrian state news agency SANA gave a death toll of 32 people and blamed the bombing on terrorists whom it says are behind a 22-month rebellion against President Bashar al-Assad.
The Observatory also reported deadly battles between mostly Sunni anti-government rebels and minority Kurdish fighters in the northeastern town of Ras al-Ain, on the border with Turkey.
It said at least 56 fighters have been killed in a week of fighting in the area. Syria's minority Kurds have largely remained on the sidelines of the majority-Sunni led rebellion, but have long sought greater autonomy from Damascus.
The Observatory said pro-Assad troops and rebels engaged in more battles in Damascus province on Tuesday.
Dozens of Russians boarded buses from Syria to neighboring Lebanon in the first evacuation organized by Moscow since the start of the Syrian uprising in 2011.
The Russian government had sent two planes to the Lebanese capital Beirut to fly the Russians back home. Syria's main international airport outside Damascus has been largely devoid of traffic in recent weeks due to fighting along the road to the capital.
Russia is one of the few remaining international allies of Mr. Assad's government. But, it has been distancing itself from the Syrian leader, acknowledging that he may be ousted by the uprising.
Separately, U.N. Secretary-General Ban Ki-moon called on U.N. members to send senior delegations to an international donor conference for Syria, to be held in Kuwait on January 30. He said the international community must do everything it can to help Syrians in need.
The UNHCR reported Tuesday that it is dramatically scaling up its operations for Syrian refugees. The agency says it is hard to keep pace with the increasing numbers of people fleeing Syria into neighboring countries. VoA.