BEIRUT — Twin suicide bombings shook a southern Syrian city on Saturday, killing at least 20 regime troops, an activist group said.

The early morning blasts in Daraa targeted an encampment for government forces in the city, according to the Britain-based Syrian Observatory for Human Rights, which relies on a network of activists on the ground.

The explosions were followed by clashes between regime forces and rebels fighting to topple President Bashar al-Assad, said the Observatory. Its chief, Rami Abdul-Rahman, said at least 20 soldiers were killed in the blasts but the claim could not be independently verified.

The Daraa bombings come a day after as many as 11,000 people were said to have fled Syria over just 24 hours, to escape fierce fighting between rebels and government forces — the latest surge of refugees fleeing the civil war.

The flood of Syrians into neighboring Turkey, Jordan and Lebanon was "the highest that we have had in quite some time," said Panos Moumtzis, the U.N. refugee agency's regional coordinator for the region said Friday.
The state-run news agency SANA said Saturday's explosions caused multiple casualties and heavy damage, but did not provide further details.

Daraa was the birthplace of the uprising against Assad, which erupted in March 2011. The conflict began largely with peaceful protests against Assad's rule but turned bloody after rebels took up arms in response to the regime's crackdown.

"I heard two very loud explosions and a third smaller one followed by bursts of gunfire," said Mohammad Abu Houran, an activist in Daraa. He said the first two were likely car bombs and the third a mortar shell or rocket propelled grenade.

Abu Houran said black smoke could be seen over the high-security area, which was sealed off. Heavy shooting could be heard from the area for about 10 minutes after the explosions, he added.

The targeted area is considered a security zone that houses a branch of the country's Military Intelligence as well as an officer's club where dozens of regime troops are based. Around 30 tanks that regime forces use to shell Daraa and surrounding areas are also stationed in a nearby stadium, activists said.

Despite gaining control over large swathes of territory, particularly in the country's north, Syria's rebels are far outgunned by the military, which has increasingly relied on airstrikes against rebel strongholds.

The Syrian opposition, which is deeply divided and plagued by rivalries, says it needs weapons to break the military stalemate and defeat Assad. The rebels' Western backers have been reluctant to send weapons to the opposition fighters, for fear they will fall into the wrong hands.

Activists say more than 36,000 people have died in Syria during the nearly 20-month-old conflict.

About 2,000 to 3,000 people are fleeing Syria daily, and the recent surge brings the number registered with the United Nations to more than 408,000, said Moumtzis.

The largest flow into Turkey came from the fighting at Ras al-Ayn in the predominantly Kurdish oil-producing northeastern province of al-Hasaka, where rebels were fighting government forces.