A huge fire has broken out at Iran's Evin prison, where political prisoners and anti-government activists are kept in the capital Tehran.
Online videos and local media reported gunshots, as nationwide protests entered a fifth week.
At least eight people have been injured in the fire, according to the Islamic Republic News Agency (IRNA), which said no fatalities have been recorded.
It is unclear what caused the blaze and the events unfolding within the prison's walls on Saturday.
Shots continued to ring out as plumes of smoke engulfed the sky in Tehran and alarms sounded.
However, the US-based Centre for Human Rights in Iran said an “armed conflict” broke out within the prison walls. It added shots were first heard in ward seven of the jail. The information has not been independently verified.
The unrest at Evin prison come as anti-government protests continued across Iran in a movement sparked by the death last month of Mahsa Amini, a 22-year-old who had been arrested by Iran’s morality police for not wearing a hijab.
Protesters reportedly chanted “down with the dictator” on the streets of Ardabil in the northwest of the country. State media quoted a security official blaming “criminal elements” for Saturday’s unrest.
The official said calm had returned, but one witness said gunfire could still be heard.
“Roads leading to Evin prison have been closed to traffic. There are lots of ambulances here,” a witness told Reuters news agency. “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. Ambulances are here too,” they said.
The activist website 1500tasvir shared video footage it said showed special forces on motorbikes heading for the prison.
At least 233 protesters have been killed since demonstrations swept Iran on 17 September, estimates from the US-based rights monitor HRANA show. The group said 32 among the dead were below the age of 18.
Public anger over Amini’s death saw girls and women to remove their mandatory headscarves and cut their hair on the street in a show of solidarity.
Other segments of society, including oil workers, have also joined the movement, which has spread to at least 19 cities, becoming one of the greatest challenges to Iran‘s theocracy since the country’s 2009 Green Movement.
Riots have also broken out in prisons, with clashes reported between inmates and guards in Lakan prison in the northern province of Gilan recently.
Iranian authorities have dismissed the unrest as a plot perpetrated by the West, without providing evidence.
The government by arresting activists and protest organisers, reprimanding Iranian celebrities for voicing support, even confiscating their passports, and using live ammunition, tear gas and sound bombs to disperse crowds, leading to deaths.
