A massive car bomb has killed 18 people in the village of Kafat in Syria's central Hama province, the Syrian Observatory for Human Rights NGO said.
The monitoring group said women and children were among the dead in the blast, which was heard in the nearby city of Hama.
Syrian state television also reported the attack in Kafat, which is under government control.
It said 16 people had been killed in a "terrorist explosion" in the village, adding that there were tens of injuries.
The Observatory said the death toll could rise because many of those wounded in the blast were in critical condition.
Those killed came from different sects and included Sunni Muslims, as well as Ismailis and Alawites, who follow different offshoots of Shia Islam.
President Bashar al-Assad and many of his inner circle are from the Alawite community.
Meanwhile, Germany will help destroy Syria's arsenal of chemical weapons materials as part of an international disarmament programme, Foreign Minister Frank-Walter Steinmeier said.
The new Social Democrat minister said countries with the technical capacity to help should not refuse.
"Therefore we in the German government have decided not to shirk our responsibility and to make our contribution. That means getting rid of part of the chemical waste," he said at a news conference with his Danish counterpart.
"The German armed forces have the technical capacity to do this in Munster," Steinmeier said.
Syria has agreed to abandon its chemical weapons by June after a sarin gas attack last August that Western nations blamed on President Bashar al-Assad's forces. Damascus blamed the rebels for the attack.
It has declared 1,300 tonnes of weapons to the Organisation for the Prohibition of Chemical Weapons which is arranging for them to be destroyed abroad.
This week some chemical weapons materials started moving out of the country onto a Danish ship.
Government sources said Chancellor Angela Merkel had agreed the move with Steinmeier and Defence Minister Ursula von der Leyen yesterday.
The decision could be controversial in Germany, which has a strong pacifist and anti-nuclear movement and has been reluctant to get involved in foreign missions, especially in the Middle East, since the end of World War II.
The sources said several hundred tonnes of very diluted materials, rather than chemical weapons, could come to Munster in northern Germany, home to a big army base.