At least three people were critically injured in a blast on Wednesday in the province of Aleppo in northern Syria, SANA news agency reported.
The explosion also destroyed the nearby buildings.
According to SANA, the explosive device was detonated by members of an “armed terrorist” group, which was accused by the authorities of the “systematic escalation ... that aims to foil the mission of the UN special envoy Kofi Annan.”
On Tuesday, a bomb placed under a military car exploded in the center of the Syrian capital of Damascus, injuring three people.
The ceasefire, part of Kofi Annan’s peace plan, came into force in Syria on April 12, although there have been reports of numerous violations of the truce by both government and opposition forces.
Syrian and foreign-based rights groups have accused Syrian government troops of executions and torture. Damascus says it is fighting “terrorists” and that some 2,000 members of the security forces have been killed in the violence.
More than 9,000 people have been killed in Syria since the outbreak of a popular uprising against President Bashar al-Assad last March, according to the UN.
Moscow has twice vetoed UN Security Council resolutions over what it called pro-rebel bias since the start of the uprising against Assad, but gave its full backing to Kofi Annan’s peace plan.