A team of Al Jazeera journalists, reporting from Syria's western province of Hama, has suffered a barrage of sniper fire that has killed a local guide who was working with the group.
Abu Yezen al-Hamoui, a local Syrian journalist who had been working with Al Jazeera correspondents, was killed in the attack on Wednesday.
Activists said they saw al-Hamoui's body been taken away following the attack. Al Hamoui's death takes the number of journalists killed in 2012 to at least 28, the Committee To Protect Journalists (CPJ) said.
At least 20 people, including eight children, were also killed in a separate attack as Syrian army tanks shelled a village in the northern province of al-Raqqa, an activist group said.
Dozens of other civilians were also injured by the government's attacks in the village of Qahtania on Wednesday, the Syrian Observatory for Human Rights reported.
"At least 20 people, among them eight children and three women, were killed in shelling by regime forces of farmlands in Kahtaniyeh village, west of the city of Raqqa," the UK-based group said.
Raqqa has seen an escalation of violence in recent months after rebels have launched an assault to oust regime forces from several areas of the province, strategically located on the Turkish border.
Meanwhile, the head of Syria’s military police defected from President Bashar al-Assad's government and accused the army of having turned into "murderous gangs", according to a security source in an online video.
In the video circulated by opposition activists, the military-clad officer said: "I, General Abdel Aziz Jassem al-Shallal, commander of Syrian military police, announce that I am defecting from the regime army, to join the people's revolution."
"The army has deviated from its essential mission, which is to protect the country, and it has morphed into murderous, destructive gangs," Shallal charged in the video published on the internet video-sharing website YouTube.
"The destruction of cities and villages, and the commission of massacres against our people, defenceless civilians, who took to the streets calling for freedom" prompted Shallal to defect, he said.
His defection comes as military pressure builds on the regime, with government bases falling to rebel assault near the capital Damascus and elsewhere across the country.
Shallal's defection takes the number of senior military and security defections since the crisis began in March 2011 to 54.
A Syrian security source confirmed the defection but played down its significance, saying that Shallal was due to retire and had defected to "play hero".
Al Jazeera’s Mohamed Vall reporting from Beirut said: “Since the defection of the Syrian Prime Minister in August this could be one of the most important.
“There is a pattern of Syrian officials trying to play down this kind of defection. They have said he was on the verge of retiring and his defection is not significant.
“Defections of this kind usually happen when the regime and its defences are crumbling,” he added.
Thousands of Syrian soldiers have defected over the past 21 months and many of them are now fighting against government forces.
Many have cited attacks on civilians as the reason they switched sides.
The violent standoff in Syria which started 21 months ago has now claimed an estimated 45,000 lives.