At least four Iranian inmates died in a fire in Tehran’s notorious Evin prison overnight, the judiciary said Sunday, further stoking tensions one month into protests sparked by the death of Mahsa Amini. The Iranian authorities blamed the fire on “riots and clashes” among prisoners, but rights groups said they had little faith in the official version of events. “Four prisoners died due to smoke inhalation caused by the fire, and 61 were injured,” the judiciary authority’s website Mizan Online reported. Four others were in “serious condition” and that the fire had been extinguished, it added. Prisoners’ relatives and rights groups voiced grave fears for the inmates. Gunshots and explosions were heard during the blaze from inside the complex, illuminated by flames and smothered by smoke, in video footage posted on social media channels. The fire came after four weeks of protests over the death of 22-year-old Amini, after her arrest for allegedly violating Iran’s strict dress code for women. The wave of demonstrations has turned into a major anti-government movement in the Islamic republic, confronting its clerical leadership with one of its biggest challenges since the ousting of the shah in 1979. Evin, infamous for the ill-treatment of political prisoners, also holds foreign detainees and thousands facing criminal charges. Hundreds of those arrested during the recent demonstrations and in a crackdown on civil society have been sent there. “We do not accept official explanations” the Norway-based non-government group Iran Human Rights (IHR) said about Iran’s official comments, adding that it had received reports that guards had sought to “incite” prisoners. There were also reports, backed by images, of explosions rocking the inside of the prison complex, gunshots heard and even a projectile being fired from outside into the jail. “Prisoners, including political prisoners, are completely defenceless inside that prison,” said Hadi Ghaemi of the New York-based Center for Human Rights in Iran. Iranian rights activist Atena Daemi, herself a long-time inmate of Evin, wrote on Twitter that in the early hours of Sunday several buses and ambulances were seen leaving the prison. She said that some prisoners in Ward 8, that houses political detainees, had been transferred to another jail. Citing a Tehran prosecutor, the official IRNA news agency said the clashes at Evin had “nothing to do with the recent unrest in the country”. The four inmates who died had been convicted of robbery, Mizan said. Evin prison holds French-Iranian academic Fariba Adelkhah and US citizen Siamak Namazi, whose family said he was taken back into custody days ago after a temporary release. Namazi’s US attorney Jared Genser said he had spoken to his family, and that he was unharmed. Australian academic Kylie Moore-Gilbert, who was held in Evin for most of her 800-plus days behind bars in Iran, told AFP she had heard that all the women political prisoners were safe. But supporters of Austrian prisoner Massud Mossaheb said he was suffering from the effects of smoke inhalation and tear gas.