Iranian prime minister Ali Razmara is assassinated by Khalil Tahmasebi, a member of the Islamic fundamentalist Fada'iyan-e Islam, outside a mosque in Tehran.

Ali Razmara, also known as Haj Ali Razmara, was an Iranian military officer and politician who served as the prime minister of Iran from 1950 to 1951.

Khalil Tahmasebi was a carpenter and member of the Iranian fundamentalist group Fadayan-e Islam, which has been described as "the first Shiite Islamist organization to employ terrorism as a primary method of political activism." On behalf of this group, Tahmasebi who was waiting in the crowd on 7 March 1951 when the Iranian Prime Minister, Ali Razmara, visited the Shah Mosque for a memorial service, fired three shots, assassinating Razmara. He was arrested at the scene. He was described as a "religious fanatic" by The New York Times. In 1952, he was freed by the Iranian Parliament during the premiership of Mosaddegh, his pending death sentence was quashed, and he was declared a "Soldier of Islam." According to Time, Tahmasebi "promptly rushed to the Hazrat Abdolazim shrine, wept joyously and said: 'When I killed Razmara, I was sure that his people would kill me.'" Following the 1953 Iranian coup d'état, Tahmasebi was re-arrested and tried for the assassination of Razmara; he was executed in 1955.

Fadayan-e Islam is a Shia fundamentalist group in Iran with a strong activist political and terrorist orientation. The group was founded in 1946, and registered as a political party in 1989. It was founded by a theology student, Navvab Safavi. Safavi sought to purify Islam in Iran by ridding it of 'corrupting individuals' by means of carefully planned assassinations of certain leading intellectual and political figures.

Tehran is the capital and largest city of Iran. It is also the capital of Tehran province and the administrative center for Tehran County and its Central District. With a population of around 9.8 million in the city, and 16.8 million in the metropolitan area, Tehran is the most populous city in Iran and Western Asia, the second-largest metropolitan area in the Middle East after Cairo, and the 24th-most-populous metropolitan area in the world. Greater Tehran includes several municipalities, including Karaj, Eslamshahr, Shahriar, Qods, Malard, Golestan, Pakdasht, Qarchak, Nasimshahr, Parand, Pardis, Andisheh and Fardis.