A day after an Al-Qaeda front group took control of the north Syrian town of Azaz, on the Turkish border, residents on Thursday shared online messages expressing their resentment and anger.
The jihadist Islamic State of Iraq and the Levant (ISIS) took control of Azaz after an hours-long battle against what had been the town's main fighting group, the Northern Storm brigade.
Youth activists launched an online campaign entitled "ISIS doesn't represent me".
"I hope Azaz turns into ISIS' burial ground," said one activist posting on Twitter.
"They failed against the Americans in Afghanistan, and against the Iranians in Iraq. Now they are here to bully the Syrians, who are fighting a criminal regime," said another.
According to the Syrian Observatory for Human Rights, Azaz was calm on Thursday.
It was unclear whether the Northern Storm brigade, a unit of the main rebel fighting group the Free Syrian Army (FSA), had withdrawn completely from the town after Wednesday's battles, but according to activists on the ground all checkpoints were being manned by ISIS.
The Observatory meanwhile reported that rebel fighters from Liwa al-Tawhid, one of Aleppo province's most powerful groups and also allied to the FSA, had arrived in the area.
According to a Liwa al-Tawhid spokesman, the group "will work to try and calm the situation...
"We are doing our best to solve the differences and to find a solution that satisfies everyone," he told AFP via the Internet.
Liwa al-Tawhid deployed fighters to Azaz after the Northern Storm brigade issued a statement appealing for help.
Meanwhile, an online activist said he feared ISIS would try to impose Islamic law in Azaz.
"Sharia law would only be imposed to allow the killing of people, and we don't want that," he said.
Another activist echoed a common claim that ISIS is working hand in glove with President Bashar al-Assad's regime, and was mirroring its methods by "attacking field hospitals, detaining doctors and killing activists".
Activists said the battle for Azaz began when jihadists broke into a field hospital, searching for a German doctor.
Another version of Wednesday's events says the fighting broke out when a Northern Storm rebel stepped in to defend a German journalist from kidnap by ISIS.
Starting Wednesday, Turkey temporarily closed down the nearby border crossing of Bab al-Salameh, according to local rebels.