16 October 2013
Last updated at 08:30 GMT
The area is in rebel-held territory but close to an army outpost.
Activists blamed regime forces for planting a bomb.
More than 100,000 people have been killed in the fighting that has ravaged Syria for two-and-a-half years - with civilians often in the firing line.
The uprising against President Bashar al-Assad's regime began in Deraa.
The Observatory said six women were also among the victims of the overnight bus blast.
A government battalion is positioned in Tal al-Jumua, "and is under siege by rebel forces. Activists blamed regime troops for planting the explosives", said the Observatory.
Bus explodes in Syria's Deraa province, 'killing 21'
At least 21 people have
been killed by an explosion that struck a bus in the southern Syrian
province of Deraa, say activist groups.
"Four children and six women [were killed] in a blast that
detonated as their vehicle went past Tal al-Jumua" in the Nawa area,
said the UK-based Syrian Observatory for Human Rights. The area is in rebel-held territory but close to an army outpost.
Activists blamed regime forces for planting a bomb.
More than 100,000 people have been killed in the fighting that has ravaged Syria for two-and-a-half years - with civilians often in the firing line.
The uprising against President Bashar al-Assad's regime began in Deraa.
The Observatory said six women were also among the victims of the overnight bus blast.
A government battalion is positioned in Tal al-Jumua, "and is under siege by rebel forces. Activists blamed regime troops for planting the explosives", said the Observatory.
