There has been an outpouring of grief and anger on Twitter after Islamic State (IS) militants were reported to have publicly executed an Iraqi journalist who refused to work with the group.

Raad al-Azzawi, 37, was shot by IS gunmen on Friday in Samra, a village in Iraq’s Salaheddin governorate, relatives told AFP. They said he was killed along with his brother and two other civilians.

“They came to his home and took him and his brother,” one relative said on condition of anonymity. “He did nothing wrong: his only crime was to be a cameraman. He was just doing his job.”

Azzawi, a father of three, worked for local news channel Salaheddin, whose headquarters were the target of two suicide bombers last December in an attack that killed five journalists. IS had accused the channel of “distorting the image of Iraq’s Sunni community.”

Media watchdog Reporters Without Borders (RSF) said Azzawi had been detained by IS on 7 September. RSF reported IS had threatened to execute him because he had refused to work for the group.

Twitter users have widely shared a photo of the slain journalist, calling on the world to show similar respect to him as done for other media workers executed by the IS group.

#Iraqi journalist killed by #ISIS today was Raad al-Azzawi, let show him the same respect we give to western journos pic.twitter.com/1DxUXg9v6J — Conflict News (@Conflicts) October 10, 2014

RIP Raad al-Azzawi - #Iraq journo murdered by #ISIS in #Iraq - Another nail in the coffin of freedom of expression http://t.co/385G2OBfuA — Donatella Rovera (@DRovera) October 11, 2014

The very good Raad al-Azzawi, killed by ISIS. A great Iraqi journalist, superb cameraman. pic.twitter.com/WhZfmQpj0V — Vijay Prashad (@vijayprashad) October 11, 2014

IS previously released two videos showing the beheadings of American journalists James Foley and Steven Sotloff. The group said they had killed the journalists in retaliation for US-led air strikes against the group in Iraq and Syria.

Two British aid workers have also been executed by them, David Haines and Alan Henning, while they have threatened another American, 26-year-old Abdul-Rahman Kassig with beheading in their latest video.

Kassig is an American humanitarian worker and recent convert to Islam. His family and friends have made public appeals for IS to release him.