Iran's state agency has announced that four prisoners have been killed, and 61 have been injured at an Evin Prison fire.
According to the report, the four prisoners died due to smoke inhalation caused by the fire. And of 61 others were injured - with 51 of these treated on an outpatient basis, the news agency said today.
Judiciary website Mizan.news said today that the four inmates who died were in prison on robbery convictions.
Evin Prison is located in the Evin neighborhood of Tehran, Iran. It has been historically known as the primary site for the housing of Iran's political prisoners, journalists and foreign nationals since 1972.
A video was shared on social media on Saturday, which showed black smoke billowing from the facility, with gunshots and explosions being heard in the area of the prison.
The fire started at around 10pm local time (6.30pm GMT), Al Jazeera has reported, and added that it involved different units of the prison.
But after several hours, the fire was extinguished and no detainees escaped, state media also said. They added the blaze broke out after a fight between prisoners - in an apparent attempt to distance the events there from the ongoing protests.
In the clip, "regime enforcers on motorcycles" can be seen racing towards the prison, as residents shout "death to the dictator" - which is one of the main slogans of the anti-government protest movement.
One witness told Reuters news agency that yesterday: "Roads leading to Evin prison have been closed to traffic. there are lots of ambulances here. Still we can hear gunshots."
Activist website 1500tasvir reported: "Gunshots can be heard from Evin Prison and smoke can be seen".
And another witness told Reuters: "Families of prisoners have gathered in front of the main door of Evin prison. I can see fire and smoke. Lots of special forces. Ambulances are here too."
The incident comes as the Islamic republic has been struggling with one of the biggest and most long-lasting protests in its 43-year-old history.
Iran has been gripped for weeks by anti-government protests, as they first erupted last month following the death of 22-year-old Kurdish Iranian Mahsa Amini, who was arrested for violating the Islamic Republic's strict dress code. Tragically, she died while in police custody on September 16.
Many Iranians were left outraged by her death, and have gone on to accuse security forces of beating her. However, Iranian authorities have insisted that she was not punished and passed away because of pre-existing conditions.
And despite hundreds of the protesters have been sent to Evin, state media has suggested the two are not linked as it not yet known whether the situation at the prison is linked to the recent demonstrations.
Al Jazeera reported on the incident and said: “Officials here say there were clashes between prisoners and that some of those prisoners have set the fire in the warehouse, in the sewing workshop of the prison.
“However some witnesses are saying that some Molotov cocktails were thrown into the prison and that they started the fire. Right after that we have seen security forces firing and also using tear gas to disperse people."
Meanwhile, earlier today, The Islamic Republic News Agency, which is the official news agency of the Islamic Republic of Iran, published a video showing parts of the prison damaged by fire.
Firefighters were seen dousing the debris with water, apparently to prevent the blaze from reigniting. It also showed the scorched walls and ceilings of a room that is said to be the upper floor of a sewing workshop at the prison.
Tehran Governor Mohsen Mansouri commented on this and said: "This fire was caused by a fight between some prisoners in a sewing workshop. The workshop was set up to create jobs."
This comes after the IRNA news agency reported, citing a senior security official, that: "The situation is currently completely under control," and calm has now returned to the prison.
Families of inmates have however gathered near the prison on Sunday, hoping for news of their loved ones inside.
Masoumeh, 49, who only gave her first name, said her 19-year-old son was sent to the prison two weeks ago after taking part in the street protests.
She said: "I cannot trust news about his health, I need to see him closely."
And Reza, who also gave only his first name, said his brother has been in Evin Prison since last year after he was involved in a violent quarrel, adding: "He did not call us in recent days and following last night's fire I am here to learn what happened to him."
The Evin Prison has long been criticised by Western rights groups.
The facility has long been known for holding political prisoners, as well as those with ties to the West who have been used by Iran as bargaining chips in international negotiations.
The Human Rights Watch has previously gone to accuse authorities at the prison of using threats of torture and indefinite imprisonment on its prisoners.
