A fire broke out on Saturday in Tehran's Evin prison, known for housing Iran's political prisoners and foreign nationals. Witnesses reported hearing gunshots fired at the prison as well.
Tehran's fire department officials has told the media that the cause of the incident was under investigation.
Iran's state-run IRNA reported there were clashes between prisoners in one ward and prison personnel, citing a senior security official. The statement released by the Iranian judiciary said that a prison workshop was set on fire after a fight among a number of prisoners convicted of financial crimes.
"Roads leading to Evin prison have been closed to traffic. There are a lot of ambulances here," a witness was quoted by Reuters.
Following the incident, families of prisoners had gathered in front of the main gate of the prison. According to them, fire and smoke came out of the prision and a lot of special forces were deployed on the scene.
Meanwhile, the security officials said that the situation has been brought under control.
The videos that came out on Sunday revealed fire and smoke emerging from the prison premises. Firemen were seen at work struggling to doze the fire.
Riot police were seen riding on motorbikes toward the facility and witnesses reported that the internet was blocked in the area.
According to reports, people from the nearby buildings were heard chanting 'Death to Khamenei'.
Earlier protests had erupted across Iran over the death in detention of Mahsa Amini, a 22-year-old Kurdish-Iranian woman. She was arrested by Iran's morality police in Tehran for violating the Islamic Republic's strict dress code. Iran's government insists Amini was not mistreated in police custody, but her family says her body showed bruises and other signs of beating after she was detained.
These protests posed serious challenges to the Islamic Republic, with demonstrations spreading across the country and people chanting for the death of Supreme Leader Ayatollah Ali Khamenei.
Meanwhile, Tehran prosecutor Ali Salehi said that "peace" had returned to the prison and that the unrest was not related to the protests which have swept the country for four weeks.
The prison fire occurred as protesters intensified anti-government demonstrations along main streets and at universities in some cities across Iran on Saturday.
At least 233 protesters have been killed since demonstrations swept Iran on September 17, according to US-based rights monitor HRANA. The group said 32 among the dead were below the age of 18. Earlier, Oslo-based Iran Human Rights estimated 201 people have been killed.
Public anger in Iran has coalesced around Amini's death, prompting girls and women to remove their mandatory headscarves on the street in a show of solidarity.
Evin Prison, which holds detainees facing security-related charges and include dual citizens, has been charged by rights groups with abusing inmates. 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.