The administration yesterday attributed a massive fire at Iran's most notorious prison for political opponents to a brawl between inmates.

Four prisoners were killed and 61 others were injured in a fire at Tehran's Evin prison on Saturday night, following weeks of unrest prompted by the death of a young woman in police custody.

Since the death of Mahsa Amini (22) in the custody of the morality police on September 16, Iran has been shaken by protests, which pose the greatest challenge to the Iranian regime in years.

The prison is a symbol of the regime's intolerance of dissent as it contains hundreds of political detainees.

As smoke billowed from the prison and flames illuminated the night sky, the administration said the fire was caused by prison "thug" activity and was unrelated to recent protests. Human rights organizations contested the official version of events, but it remained unclear Sunday night exactly what sparked the unrest.

In video footage of the fire, gunfire, explosions, and cries of "Death to the dictator" could be heard. "Death to the dictator" was one of the chants screamed during anti-government demonstrations. Iran's president slammed Joe Biden last night for encouraging "chaos, terror, and destruction" in Iran.

Initial reports indicated that approximately nine persons were hurt in the fire and that no one fled. Later, the numbers were changed to four fatalities and 61 injuries.

Evin prison, known for its use of torture, is home to intellectuals, dissidents, dual nationalities, and anybody deemed a regime opponent.

At Evin, hundreds of Amini demonstrators have been imprisoned.