(CNN) -- U.N. observers who were stranded overnight in a Syrian town after their convoy struck an explosive device have made it safely to the city of Hama, the United Nations said Wednesday.
The six observers were in Khan Sheikhoun, part of Idlib province, when they were attacked, said Ahmad Fawzi, spokesman for U.N.-Arab League special envoy Kofi Annan.
No U.N. personnel were injured in the explosion Tuesday, but three vehicles were damaged, Fawzi said.
A bombardment by Syrian forces continues in Khan Sheikhoun, according to the opposition Local Coordination Committees of Syria. The regime is using "all kinds of heavy weapons, the LCC said.
Opposition activists reported another day of widespread violence in many parts of the country that left at least 15 people dead.
Nine people died Wednesday in Khan Sheikhoun, according to the opposition Syrian Observatory for Human Rights. A child and a civilian were among them. Four died of wounds suffered Tuesday as government forces attacked the area, the group said.
Three people, including a young girl, were killed Wednesday when government forces shelled a camp for displaced residents, opposition activists said.
The camp in Daraa is for displaced Syrians from the Golan Heights, who were not fleeing violence from the current unrest in Syria, according to the observatory.
Syria, on state-run news agency SANA, said 11 "army, law enforcement and civilian martyrs" were buried Wednesday.
Also, 250 citizens "who were involved in the recent events and whose hands are clear of the Syrian blood were released on Wednesday," SANA said.
Syria blames the violence in the country on "armed terrorist groups."
SANA also reported that three terrorists -- one from Libya and two from Tunisia -- "confessed that they infiltrated into Syria through the Turkish borders in order to carry out terrorist attacks in coordination with al Qaeda and militias of the so-called free army."
The rebel Free Syrian Army has been battling regime forces.
Opposition groups say President Bashar al-Assad's government has been trying to mar their efforts with false accusations of links to terrorism.
Syria has met their call for a new government and political reforms with a brutal, violent crackdown, opposition activists say.
The LCC on Wednesday reported raids, the burning of homes, random arrests and more throughout the country. Ambulances were prevented from aiding the wounded in some places, the group said.
The Tuesday attack on the U.N. convoy took place around the same time government forces fired on a nearby funeral procession, according to opposition activists.
At least 23 people were killed and 100 were injured in that attack, said the opposition group Avaaz.
The LCC described dozens of people falling to the ground after government forces fired on them using heavy machine guns.
Videos posted on YouTube purported to show what happened. CNN cannot confirm their authenticity.
The United Nations estimates that at least 9,000 people have died in the 14-month crisis, while opposition groups put the death toll at more than 11,000.
CNN cannot independently verify reports of deaths and violence because the Syrian government has severely restricted access by international media.
Meanwhile, a Western diplomat confirmed to CNN that according to a confidential U.N. draft report, Iran is violating a Security Council ban on weapons exports and that Syria is the top recipient for those arms.
The report, which was drafted by a panel of experts and submitted to the Security Council's sanctions committee on Iran, describes three large seizures of Iranian weapons shipments within the year. The diplomat confirmed that report claims two of those seizures involved the Syrian Arab Republic.
CNN's Samira Said, Amir Ahmed and Joe Vaccarello contributed to this report.