TEHRAN — Iran's notorious Evin prison appears to be alight, with footage posted online showing flames and smoke billowing from the area.

Gunshots and alarms have been reported as coming from the jail, the primary site for detaining political prisoners.

State media said calm has been restored to the prison, and has blamed "criminal elements" for the blaze.

The fire comes as Iran continues to be rocked by its most intense unrest in decades. Protests have been taking place across the country once again on Saturday.

The protest first erupted last month when anger over the death in police custody of 22-year-old Kurdish Iranian Mahsa Amini boiled over.

Officials said she died from an underlying health condition, but her family said she died after being beaten by morality police.

Despite the authorities blocking Internet access, reports from the mainly-Azeri city of Ardabil say security forces have opened fire on the demonstrators on Saturday.

The situation there is tense, after the police attacked protesting schoolgirls earlier in the week.

It is unclear what was the cause of the fire at Evin prison, but there are further reports that special forces have been deployed to the area. Firefighters are at the scene, according to state media. — BBC