One of Syria’s most prominent activists, known for eye-catching protest banners and influential “Radio Fresh” broadcasts, has been assassinated in the rebel-held northern enclave in Idlib province.

Raed Fares took on the regime of Bashar al-Assad and the proliferation of Islamist extremists that grew out of Syria’s civil war with equal energy and commitment. Fellow activist Hamoud Jneed was murdered with him on Friday morning by gunmen who have not been identified.

Their killers waited in a van outside an office the two men shared, followed them through the market, attacked their car then shot them when they tried to escape, according to a friend from their hometown.

Fares lived in the small northern town of Kafranbel, and helped put it on the international map after Syria’s uprising began in 2011, with a series of sometimes witty, sometimes angry but always powerful posters he organised for demonstrations.

“Syria has two conflicting parties: people who try to survive, and a regime that tries to crush them,” read one example from the first years of the war, spelled out in the block letters that became Fares’s trademark. They helped earn the town the nickname “the conscience of the revolution”.

Fares was drawn into the movement against Assad because of a childhood spent watching the murderous legacy of the Syrian regime, he told the Oslo Freedom Forum last year.

“The question is, was it worth starting a revolution and confronting Assad?” he asked, then answered himself: “It was indeed important.”

Facebook Twitter Pinterest Hamoud Jneed. Photograph: AP

As the war escalated and armed fundamentalists proliferated, he found himself fighting on two fronts, squeezed between the dictatorship he first rose up against and the increasingly extremist armed groups spawned by the civil war, including Isis and former al-Qaida affiliate Hayat Tahrir al-Sham.

“The truth is Syrians are victims of two forms of terrorism. From one side Assad’s terrorism, and from the other, Isis and other extremists’ terrorism,” Fares said.

The offices of the civil society organisation he founded had been bombed by Assad and raided by Isis. Fares himself was targeted by assassins in 2014 and barely escaped with his life. He was arrested by al-Qaida, kidnapped and tortured, before being released.

Throughout it all, he continued his work campaigning for education, democracy, women and children and, most of all, an end to the bloodshed.

Increasingly disillusioned with the west, after its failure to intervene against Assad despite the president’s use of chemical weapons against civilians, he never lost his faith in the Syrian people, even as his struggle looked increasingly desperate.

“We have decided to guide our future and our destiny with our own hands,” he said in Oslo. “Revolutions are ideas and ideas cannot be killed by weapons.”

The deaths of Fares and Jneed were widely mourned on social media by friends, fellow activists and analysts. In Kafranbel, locals said more than 2,000 people gathered for his funeral, including many who travelled from other towns.

“We feel extreme sadness for Raed and Hamoud and fear for ourselves,” said one friend who asked not to be named. “This was planned, and it sends a message to all activists to be silent.”