Ward 350 is managed by the prison authority, while Wards 209 and 2A are respectively controlled by the Ministry of Intelligence and the Islamic Revolutionary Guard Corps' intelligence office.

The serious clash took place inside Ward 350, where many political prisoners are detained. The guards attempted to search prison cells, but the prisoners refused to exit their cells and demanded to be present for the searches, since they believe personal items are often stolen during this process. Upon the prisoners' refusal, the guards first threatened, then beat them.

Evin prison, one of Iran's most notorious detention facilities, witnessed an unprecedented attack April 17 by security guards on political prisoners that has left dozens injured and four hospitalized.

The prisoner, whose name we cannot release due to security reasons, said: “The guards came in starting around 10 a.m., demanding to search the rooms. We refused to leave our rooms, so they threatened us and said they will punish us. They said they can send us to exile [domestic exile prison near Iran’s borders], but we resisted and did not leave the rooms. Finally, they told us to leave the rooms for recess; however, many guards had lined up on two sides of the corridor, forming a ‘tunnel,’ and were beating the prisoners with police sticks. The way they treated us was worse than the way the Iraqi government treated Iranian war prisoners.”

According to the source, political prisoner Gholamreza Khosravi is among the severely injured. Many others were moved to solitary, including: Asadollah Hadi, who suffers from heart problems; Reza Akbari-Monfared; Abolghassem (Javad) Fouladvand; Mehrdad Ahankhah; Asadollah Assadi; Soheil Arabi; Amir Dorbin-Ghaziani; and Mohammad Davari. During the clashes, Soroush Sabet's skull was cracked and Semkou Khelghati was badly beaten and his clothes torn during a fight with intelligence officers.

“They broke our plates and belongings,” the source said. “The corridor was covered in blood and it was quite horrible.”

Many of the prisoners not in solitary remain defiant and are considering a collective response, either through a mass hunger strike or the publication of an open letter about prison guard violence. The prisoners are currently in contact with political activists on the outside and said there will be a response soon.

When asked about the reasons behind such an unprecedented act of mass violence, the source answered: “Perhaps it is a reaction to the increasing international pressures.”

Mohammed Pourabdollah, a student activist who served part of his jail sentence at Evin, described Ward 350 to Al-Monitor: “This political ward is constantly under surveillance. Phones are disconnected and there is CCTV everywhere. The general environment is intensely security-oriented. They fear collective political actions, and the operatives of the Ministry of Intelligence are everywhere, surveying all of the prisoners' actions.” He said the Ministry of Intelligence does not want any contact between the political prisoners and the outside world, and wishes for the present contacts to be "cut off."

Kouhyar Goudarzi, a human rights activist and former prisoner of Ward 350, told Al-Monitor: “Prison officials are quite sensitive about any form of noncompliance. They are very worried about any form of civil disobedience from the political prisoners. The same thing happened three years ago, when prison officials wanted to move 10 prisoners to solitary, but others resisted and prevented this. So, the special forces moved in and started beating the prisoners.”

In recent years, prison officials have tried hard to cut off contacts between the political prisoners and the outside world. However, they have not succeeded. Many prisoners continue their political activities by writing open letters and newspaper articles.

Evin has witnessed some of Iran's most notorious single cases of abuse. In 2003, Zahra Kazemi, an Iranian-Canadian journalist, was killed as a result of torture during her interrogations at Evin. Her death was investigated by members of parliament, but Judge Saeed Mortazavi, a key figure in the case of her death, was never prosecuted or convicted. Additionally, Hoda Saber, another political prisoner, died of a heart attack during a hunger strike. Sattar Beheshti, the blogger whose death became a scandal for the Internet Police Force, also died inside the prison.

Maziar Bahari, an Iranian-Canadian journalist and Newsweek reporter, spent time inside the prison, and later published a memoir titled Then They Came for Me. The three Americans arrested at the Iran-Iraq border — Shane Bauer, Joshua Fattal and Sarah Shourd — spent most of their time in captivity inside Evin. They published their own memoir, A Sliver of Light. They have testified about the harsh treatment, torture and psychological traps at Evin.

Amnesty International has issued a letter of concern urging Iranian citizens to write to officials asking for injured prisoners to be provided with medical provisions. In the letter, officials are discouraged from torturing or mistreating prisoners in solitary confinement. In the first official reaction from the government, the head of the prison administration, Gholamhossein Esmaeeli, denied any form of physical punishment by the guards against the prisoners of Ward 350.