Six soldiers also died when a bomb exploded beside a lorry transporting them in Deraa.
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Some predict that Farouk Sharaa, the vice-president who comes from Deraa, may break with the regime.
Homs in central Syria and Herak and Deraa in the south were subjected to bombardment, the Observatory added.
It said the highest casualties were tracked in Deraa a rebel stronghold bordering Jordan where the uprising was ignited last year.
Similarly, demonstrations in the Syrian city of Deraa erupted in mid-March to protest against the jailing of minors for spraying graffiti.
On April 27th it was reported that 200 members of the Baath party, most of them from Deraa, had left it.
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One of the worst-hit areas recently has been Deraa, in the south.
At least two members of the rubber-stamp parliament, a tribal sheikh and several figures from the ruling Baath party in Deraa, have recently defected.
"They discriminate between the Alawites and Sunnis, " said the soldier, a 22-year-old man from the southern city of Deraa, who asked not to be named.
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Continuing army operations against rebels are also being reported in the northern city of Idlib, the southern province of Deraa, and the town of Zabadani, north of Damascus.
Separately, at least 18 people were killed in an airstrike by the Syrian regime on a rebel field hospital in the southern city of Deraa, according to the Syrian Observatory for Human Rights.
Rebels in Deraa province are among the most organized groups fighting the Assad regime in Syria, with Western-vetted military councils receiving some of the most advanced weaponry supplied by Gulf states through the Jordanian border.
The state news agency, Sana, said an army officer had been killed and 24 others injured when a bomb exploded next to a military bus in Aleppo, and that a Baath Party official had been shot dead in al-Mazarib, in Deraa province.
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