A huge fire broke out at a prison in the Iranian capital, Tehran, on Saturday night, after nearly a month of protests over the death in custody of Jina Mahsa Amini.
By Sunday morning, Iranian state television said the blaze had been extinguished.
Online videos posted to social media appeared to show smoke rising from the city's Evin prison, which holds political prisoners and dual nationals. Gunshots and chanting can be heard in the background.
The official IRNA news agency quoted an unnamed security official as saying the unrest was "under control," and that the blaze was put out, adding that it "had nothing to do with the recent unrest in the country."
The state-run judiciary news agency Mizan reported that four inmates had died from smoke inhalation and another 61 had been injured in the incident. Ten were reportedly hospitalized, of which four were in serious condition.
Rights groups said that there had been protests in solidarity with inmates of Evin prison late into the night in Tehran, with chants heard of "death to the dictator."
What happened at the prison?
The unnamed official cited by IRNA said the unrest occurred in a section of the prison holding "thugs."
The agency said it erupted due to clashes between prisoners and prison personnel in one ward. A senior security official said that prisoners set a warehouse holding prison uniforms ablaze.
The authorities claimed to have de-escalated the situation by separating the "rioters" from the rest of the inmates.
Witnesses told the Reuters news agency that roads leading to the prison were blocked, while ambulances arrived at the scene. They added that families of prisoners gathered outside the main entrance.
German Foreign Minister Annalena Baerbock pledged continued focus on the protests in Iran.
"The fire in Evin prison may be extinguished, but our attention to the people who have been detained there and their human rights will not stop," she wrote on Twitter.
Political prisoners in danger?
"Prisoners, including political prisoners, are completely defenseless inside that prison," Hadi Ghaemi, director of the New York-based Center for Human Rights in Iran (CHRI) said.
"Evin is where the Islamic Republic regime holds many political prisoners during these years. According to human rights organizations, this prison is where the regime has committed serious human rights abuses against political prisoners and critics of the government," DW's Farsi language journalist Niloofar Gholami said.
According to Gholami, Iranian human rights activists fear that the situation in Evin is "the regime's own tactic to maybe eliminate political prisoners," despite the official communications on the fire.
In 2018, the US government blacklisted the prison, citing "serious human rights abuses."