Rebels say they downed helicopter
Meanwhile, a YouTube video posted by Syrian activists Thursday claimed that rebel fighters had shot down a Syrian military helicopter, killing four crew members on board.
The Syrian Observatory for Human Rights, an opposition group, said rebel fighters shot down the helicopter north of Maarat al-Numan.
It was carrying food supplies to two regime bases, Wadi al-Deif and Al-Hamdiyeh, which have been under siege by the rebels for several months, the Observatory said.
CNN could not independently verify the claim.
The bases are strategically important to forces loyal to Syrian President Bashar al-Assad. If the rebels took them, it would enable their forces to cut off the single route in Idlib that the government uses to supply troops operating in Aleppo.
The rebels already control the border crossings with Turkey in the north, so the government would be forced to use a more difficult route going from Latakia.
In a Daraa city, opposition cites a massacre
Civilians were killed when Syrian forces used air cover to storm the city of Sanamein in Daraa province Wednesday, the opposition said. Daraa is where the anti-government uprising got going more than two years ago.
The Local Coordination Committees in Syria called the act a massacre, saying at least 60 people were killed and al-Assad's government used civilians as shields to hold off rebels.
More than 200 people were detained, homes were burned, and snipers targeted more than 10 civilian-filled cars fleeing to safety, the LCC said.
The Syrian National Coalition, representing the anti-government fighters, said the action illustrated "the lust of killing and thirst for blood in the hearts of those belonging to the criminal regime of Assad."
"The criminals shelled the town (and) then they stormed it, allowing their loyalists to commit despicable atrocities against civilians. They took hostages as human shields. They also slaughtered people and committed vandalism and theft. These despicable acts against women, children and unarmed civilians indicate how the regime is incapable to confront the men of the revolution and the free Syrian army, as well as the failure to stop the liberation of Daraa province."
At least 149 people were killed across the country on Thursday, the LCC said.