They learned to sneak into their offices in the northern city of Raqqa after midnight, and conceal their activities from their landlord. But it’s not Bashar al-Assad’s regime that they’re worried about.

The citizen journalists of the ANA New Media Association were hiding from al Qaeda-affiliated jihadists, who have become a powerful force in the area. Their precautions were not enough: On Oct. 1, members of the Islamic State of Iraq and al-Sham (ISIS) kidnapped one of ANA’s employees at a checkpoint and subsequently raided their office. They returned on Oct. 15, breaking into the office to seize the equipment the journalists had used to broadcast a radio program to the area’s residents.

The crackdown is just the latest example of the growing tension within the anti-Assad cause between Islamist radicals and more mainstream rebel groups. Last month, ISIS fighters seized the town of Azaz, near the Turkish border, from a rival militia. Sporadic clashes have broken out elsewhere across north and eastern Syria. The hostilities could deal a blow to the jihadi groups, which are gaining strength across north and east Syria — but they could also fracture the anti-Assad cause.

By going after ANA in Raqqa, ISIS is moving to squelch a vocal critic in a city that has become one of its strongholds.

“We’ve been quiet about the mistakes that have come out of the opposition — from people who claim they’re part of the opposition,” said Rami Jarrah, the co-director of ANA. “We know that the public does not support these people, but they don’t have an alternative unless we start speaking out against these groups.”

For the three months that ANA operated in Raqqa, the radio station focused its criticism on the Islamist radicals. It featured the perspective of regular Syrians who attacked ISIS, and also aired a program called “With the People” that highlighted the harassment of activists and journalists.

For nearly two years, ANA has produced content aimed at an international audience. On its YouTube channel, for example, it adds English subtitles to videos it deems important: One subtitled video shows the devastation that followed the regime’s Aug. 21 chemical weapons attack in the Damascus suburbs, while another video shows a peaceful conversation between Sunni rebels and an elderly Alawite man.

Several months ago, however, it launched radio programs aimed at providing news for Syrians inside the country, and influencing how they see the revolt. One program, for example, discussed the history and stages of the French Revolution — an effort, perhaps, to provide Syrians with some context for the length of and the changes within their own uprising.

But it was the anti-ISIS programming that caused ANA’s four citizen journalists in Raqqa to live a precarious existence, even before the raids. According to Jarrah, they first had to win the approval of Jabhat al-Nusra, which the State Department considers an al Qaeda affiliate, to bring their broadcast equipment into the area. However, they set up at a different address than the one that they gave to the jihadi group. Soon after they moved into their new offices, ISIS fighters overran the post of a rival rebel militia next to their building — ANA’s new neighbors were now precisely the people it was trying to avoid.

“It was dangerous over the past two months, and we knew so,” Jarrah said. “We spent the past two months with the guys just coming to the office to set up the broadcast, and then taking their computers and working elsewhere.”

The confrontation came to a head on Oct. 1, when ISIS fighters seized ANA staffer Rami al-Razzouk at a checkpoint, as he was traveling to the city of Tabaqa. Razzouk has not been heard of since, though ANA received unconfirmed reports that he had been beaten severely and transferred to the eastern province of Deir Ezzor. ISIS raided ANA’s offices roughly three hours after Razzouk’s capture, seizing the group’s laptops and a camera. A sharia court judge attempted to mediate, but ISIS rejected the intervention, accusing the media outlet of taking money from foreign intelligence organizations.

Prominent Syrian dissidents have also recently castigated ISIS’s behavior. Anti-Assad writer Yassin al-Haj Saleh penned an essay describing how he was forced to flee Damascus for fear of capture by the regime; when he arrived in Raqqa, where he had lived in his youth, he found himself once again forced into hiding for fear of capture by the Islamist radicals. ISIS’s name, he wrote, “befits a ghoul in one of the folktales we used to hear in youth.”

In other parts of Syria, ISIS has been responsible for some of the worst human rights violations committed by anti-Assad groups during the conflict. Human Rights Watch (HRW) detailed how ISIS fighters participated in a massacre of at least 190 civilians in pro-government villages in the province of Latakia. A rebel military leader interviewed by HRW reported that as of last month, ISIS also held over 100 hostages from the assault, whom they were attempting to exchange for their own prisoners and money.

ANA plans to re-launch its broadcast in Raqqa as soon as possible. Jarrah said the outlet is sneaking new equipment into the area, and plans to be broadcasting again within two weeks.

“I think the main lesson is that we were quiet [about ISIS’s activities] for so long, that now — when we’re being attacked, when we’re being oppressed — there are people saying ‘Well, these guys are on your side,’” he said. “But these guys were never on our side.”

This story first appeared at ForeignPolicy.com.