A fire broke out on Saturday in Tehran's Evin prison, where many of Iran's political and dual-national detainees are held, and witnesses reported hearing gunfire.
State news agency IRNA said eight people were injured in the unrest, which erupted after nearly a month of protests across Iran over the death in detention of Mahsa Amini, a 22-year-old Kurdish Iranian woman.
The protests have posed one of the most serious challenges to the Islamic Republic since the 1979 revolution, with demonstrations spreading across the country and some people chanting for the death of Supreme Leader Ayatollah Ali Khamenei.
An Iranian judiciary statement said a prison workshop was set on fire "after a fight among a number of prisoners convicted of financial crimes and theft". Tehran's fire department told state media the cause of the incident was under investigation.
The prison, located in the foothills at the northern edge of the Iranian capital, holds criminal convicts as well as political detainees.
"Roads leading to Evin prison have been closed to traffic. There are lots of ambulances here," said a witness contacted by Reuters. "Still, we can hear gunshots."
Another witness said families of prisoners had gathered in front of the main prison entrance. "I can see fire and smoke. Lots of special forces," the witness said.
A security official said calm had been restored at the prison, but the first witness said ambulance sirens could be heard and smoke still rose over the prison.
"People from nearby buildings are chanting 'Death to Khamenei' from their windows," the witness said.
Early on Sunday, IRNA carried a video it said showed prison areas damaged by fire. Firemen were seen dousing the debris with water, apparently to prevent the blaze from re-igniting.
The prison mostly holds detainees facing security charges, including Iranians with dual nationality. It has long been criticised by Western rights groups and was blacklisted by the U.S. government in 2018 for "serious human rights abuses".
Siamak Namazi, an Iranian American imprisoned for nearly seven years on espionage-related charges rejected by Washington as baseless, returned to Evin on Wednesday after being granted a brief furlough, his lawyer said.
Other U.S. citizens held in Evin include environmentalist Morad Tahbaz, who also has British nationality, and businessman Emad Shargi, according to human rights lawyer Saeid Dehghan.
He added that several other dual nationals are held at Evin, including French-Iranian academic Fariba Adelkhah and Iranian-Swedish Ahmadreza Djalali, a disaster medicine doctor.
Asked about the prison fire, U.S. President Joe Biden told reporters during a campaign trip to Portland, Oregon: "The Iranian government is so oppressive."
He said he was surprised by "the courage of people and women taking (to) the street" in the recent protests and had enormous respect for them. "It's been really amazing," he added. "They're not a good group, in the government."
U.S. State Department Spokesman Ned Price tweeted, "we are following reports from Evin Prison with urgency. We are in contact with the Swiss as our protecting power. Iran is fully responsible for the safety of our wrongfully detained citizens, who should be released immediately."
Human Rights Watch has accused authorities at the prison of using threats of torture and of indefinite imprisonment, as well as lengthy interrogations and denial of medical care for detainees.
"No security (political) prisoner was involved in today's clash between prisoners, and basically the ward for security prisoners is separate and far from the wards for thieves and those convicted of financial crimes," an unnamed official told the Tasnim news agency.
'CLERICS GET LOST'
The unrest at Evin prison occurred after nearly a month of protests across Iran since Amini - a 22-year-old woman from the country's Kurdish region - died on Sept. 16 while being held for "inappropriate attire".
Although the unrest does not appear close to toppling the system, the protests have widened into strikes that have closed shops and businesses, touched the vital energy sector and inspired brazen acts of dissent against Iran's religious rule.
On Saturday protesters across Iran chanted in the streets and in universities against the country's clerical leaders.
A video posted by the Norway-based organisation Iran Human Rights purported to show protests in the northeastern city of Mashhad, Iran's second-most populous city, with demonstrators chanting "Clerics get lost" and drivers honking their horns.
Videos posted by the group showed a strike by shopkeepers in the northwestern Kurdish city of Saqez - Amini's home town. Another video on social media showed female high school students chanting "Woman, Life, Freedom" on the streets of Sanandaj, the capital of Kurdistan province.
Reuters could not independently verify the videos. Phone and internet services in Iran have been frequently disrupted over the last month and internet watchdog NetBlocks reported "a new major disruption" shortly before Saturday's protests began.
The Iranian activist news agency HRANA said in a posting online that 240 protesters had been killed in the unrest, including 32 minors. It said 26 members of the security forces were killed and nearly 8,000 people had been arrested in protests in 111 cities and towns and some 73 universities.
Among the casualties have been teenage girls whose deaths have become a rallying cry for more demonstrations demanding the downfall of the Islamic Republic.
Protesters called on Saturday for demonstrations in the northwestern city of Ardabil over the death of Asra Panahi, a teenager from the Azeri ethnic minority who activists alleged was beaten to death by security forces.
Officials denied the report and news agencies close to the Revolutionary Guards quoted her uncle as saying the high school student had died of a heart problem.
(Reporting by Dubai bureau, additional reporting by Lucia Mutikani, Mike Stone and Jeff Mason in Washington, Writing by Dominic EvansEditing by Helen Popper, William Maclean, Paul Simao and Diane Craft)
