Residents of this rebel rear base north of the key battleground of Aleppo were cleaning up on Saturday after a Syrian regime air strike killed at least 12 people.

"This was my house. Now nothing is left," said Yussef al-Wati, an engineer, as he clambered up a once enclosed stairway that is now open to the skies.

Men from the neighbourhood lent a hand as he combed the debris for anything salvageable such as clothes and bedding.

Umm Omar, a mother of four escorted by half a dozen women relatives for moral support, took a single hard look at her own flattened home and declared: "We've lost it all, not a little bit, all."

Like many women in the town, she had taken to the relative safety of the countryside on Friday, when Muslims observe traditional weekly prayers and a day in Syria that has become synonymous with demonstrations and bloodshed.

"I have no choice but to take shelter with my relatives," she told AFP.

Al-Bab is 30 kilometres (18 miles) northeast of commercial capital Aleppo, the scene of fierce clashes on the ground between forces loyal to President Bashar al-Assad and anti-regime fighters known as the Free Syrian Army.

The town is also an FSA rear base. Commanders there have told AFP that roughly a dozen brigades use Al-Bab as a springboard for operations in Aleppo.

Although some residents put the toll from Friday's air strike that levelled several homes at up to 20 dead, a doctor at the main clinic in Al-Bab said on Saturday that 12 people had died.

"Yesterday, after prayers, the warplane appeared and started bombing peaceful demonstrators at random," said a resident who gives his name as Ibrahim.

The attack on the town of some 80,000 people came shortly after Friday prayers as worshippers streamed out from the mosques to demonstrate against Assad's regime.

"The plane started circling above us and then dropped two bombs back to back," said Wati, adding that there were eight air raids in total in a span of 10 hours.

He added that dozens of women and children from his neighbourhood took shelter in the basement of a residential building which typically houses four families, including his own. They all survived.

Six people were crushed to death in another strike on the same day, residents said, counting off the names of those killed on their finger tips. Some estimated the death toll at closer to 20.

The doctor told AFP: "Twelve people were killed."

Collapsed rooftops, exposed wires and shattered walls map the trajectory of the attack which spread terror across Al-Bab. Shattered glass and rubble pave several streets and gaping craters force cars to take detours.

AFP journalists counted at least six separate sites devastated by the blasts -- four buildings in three separate residential areas, a school and a shopping strip.

Several residents said that Al-Bab, which has had no electricity for several days, is being punished for its freedom as well as because of rebel gains in the provincial capital Aleppo.

"Is this what they call a high quality surgical operation against terrorists?" asked merchant Mahmud Ali, as he took stock of the damage to his warehouse stuffed with giant sacks of lentils.

The building's facade, little more than a sheet of corrugated metal, and a sturdy cement wall at the back have been written off as collateral damage.

"The only terrorist is Bashar al-Assad..." fumed Ali.

Another resident finished the sentence for him: "...and his pilots who are too cowardly to set foot on our streets."

But such bravado fades fast to fear when residents spot an aircraft high overhead. Too high for them to tell whether it is another warplane.

"Don't crowd, don't crowd," barked several men, their eyes glued to the small speck in the sky until it finally disappears.

Omran, a young man with slick black hair caked with white dust from his scavenging through remains, explained quietly that there would be no big funerals in Al-Bab because the people fear being targeted again.

"Each family will discreetly bury its own to avoid creating crowds," he said.

The Syrian army withdrew from Al-Bab in late July in a move that gave opposition forces control over a vast swathe of territory stretching from the outskirts of Aleppo north to the border with Turkey.

But the FSA grip on the area is tenuous, threatened by the superior firepower of Assad's forces. Residents of Aleppo province cite MiG warplanes and rocket attacks as being the most frightening.

"Assad is just furious at our freedom," Omran decided.