More than 60 people have been killed in at least two attacks near a Syrian town just captured by Turkish forces and Syrian opposition fighters from Islamic State militants, Turkey's news agency said.
Most of those killed were civilians, though two Turkish soldiers also died in the attacks as IS members retreat from one of their last remaining strongholds in northern Syria.
In a hallmark IS attack, a suicide car bomb went off outside a security office operated by the Syrian opposition in a village five miles north of al-Bab, killing 60 people.
Most of those killed in Sousian were civilians who had gathered seeking permits and escorts to return to al-Bab, a day after it was liberated from the extremist group, a Syrian military commander in the city said.
At least six fighters were among those killed in the attack, according to Turkey's Prime Minister, who spoke in Ankara.
Hours later, another car bomb attack was reported in Sousian, claiming the lives of at least eight, according to activist groups.
Despite the violence, Turkey's chief of military staff said his country had "achieved the goals" it had set for its military operation in northern Syria.
The Turkish military earlier announced that its troops and allied Syrian opposition fighters are in full control of al-Bab but that efforts to clear it of mines and explosive devices are continuing.
General Hulusi Akar spoke during a visit to the border with Syria, a day after Turkish troops and Turkey-backed opposition forces captured the town.
He did not say, however, if Turkey would end its operations in northern Syria or if it would move on to liberate other areas.
The Turkish military said that it currently controls 743 square miles in northern Syria since its incursion there last August.
The Turkey-backed operations have aimed to create a safe zone along the border, deterring from its borders Islamic State militants as well as Kurdish rebels it sees as an extension of its own insurgent group.
Turkish President Recep Tayyip Erdogan and other officials have spoken of plans to move the Turkish forces east towards the town of Manbij that is held by US-backed forces that include Syrian Kurdish fighters in a bid to oust them from the area.
Turkish leaders have also suggested that Turkish troops could take part in operations to liberate the Islamic State group's de facto capital, Raqqa.
Gen Akar said that Turkey would provide "every kind of support" to help life in al-Bab return to normal and for the local population to return to their homes.
On Friday, civilians attempting to return to al-Bab were hardest hit.
According to Mohammed al-Tawil, a leading Syrian opposition fighter north of al-Bab, a suicide attacker blew up his small pick-up truck outside a security office in Sousian village. He said the explosion went off as the opposition fighters were organising the return of civilians from al-Bab who had been displaced by the fighting for their town.
"These people have suffered a lot," Mr al-Tawil said. "They have been waiting for this moment to return home."
Mr al-Tawil, a member of the opposition al-Bab military council, said about four fighters manning the checkpoint had been killed in the attack. Mr al-Tawil, who was at the security office at the time of the explosion, said the rest of the casualties were civilians from al-Bab.
Turkey's Anadolu news agency said at least 41 wounded were taken for treatment in the Turkish border town of Kilis.
Al-Bab had been controlled by IS since late 2013. The militants finally retreated on Thursday after more than two months of intense fighting.
Al-Bab had a pre-war population of about 60,000, many of whom were displaced to neighbouring areas, including during the most recent clashes.
Footage emerging from al-Bab showed a deserted town, badly damaged by the war. At least one of the streets appeared completely wrecked, with buildings damaged or levelled on both sides.