Magnum photographer Abbas answers journalists' questions in front of some of his pictures displayed at the Islamic Institute of Culture on its inauguration day, Nov. 28, 2013, in Paris. (Eric Feferberg/AFP/Getty Images)

Abbas, an Iranian-born, single-named photojournalist who traveled the world to document wars, revolution and religious extremism, particularly among Muslims, and published his work in several books, died April 25 in Paris. He was 74.

The Magnum photographic agency, which had distributed his work for more than 30 years, announced his death. The cause was not disclosed.

Beginning in the 1960s, Abbas photographed disputes in Nigeria, Vietnam, Israel and Northern Ireland and the effects of apartheid in South Africa, but he became better known for his chilling images of Iran during the Islamic revolution of the late 1970s.

Returning to his native country, Abbas chronicled the downfall of the shah’s regime and the rise to power of Islamic clerics, led by the Ayatollah Khomeini, whom Abbas captured in an evocative portrait in 1979.

Calling himself a “historian of the present,” Abbas was in the streets of Tehran as fervent supporters of the clerics attacked people suspected of supporting the shah. He photographed the charred body of a woman who was burned after being accused of prostitution.

At times, Abbas was threatened by mobs.

“There’s always somebody saying, ‘Oh, don’t take pictures, don’t take pictures,’ ” he said in a 2015 interview with Terry Gross of the NPR program “Fresh Air.” “And I will always answer in Farsi, ‘This is for history.’ ”

In 1979, Abbas managed to get inside a morgue in Tehran, where he photographed the bodies of four Iranian generals who were executed after a secret trial. One of them was the former director of the shah’s feared secret police.

“That was a turning point,” Abbas said on “Fresh Air.” “That was my country, my people and my revolution. But this very moment, when I saw these four generals at the morgue, I decided to stay on, work as long as I can.”

Never an admirer of the shah, Abbas came to see the revolution of the ayatollahs equally as repressive.

“The whole nation of Iran,” he said, “was hostage to the extremists.”

Abbas left Iran in 1980, the same year he published his first book, which was about the country’s revolution. With Paris as his base, he traveled throughout Mexico in the 1980s, photographing the contrasts between wealth and poverty.

In 1987, he embarked on an ambitious project to document the connection between Islam and what he saw as a growing extremist ideology. Over the next seven years, he visited 29 countries, including Afghanistan, France, Indonesia, Mali, Pakistan and the United States.

“Something we learned is that the extremists always win,” Abbas told the Toronto Star in 2013. “That was my main lesson from the revolution. The extremists were prepared to kill, imprison, torture — everything. So they won.”

When Abbas published “Allah O Akbar: A Journey Through Militant Islam” in 1994, some criticized it as a dark, slanted view of Islam. After the terrorist attacks of Sept. 11, 2001, others saw the book as an early warning sign.

Abbas devoted the next few years to chronicling other religions and beliefs, including Christianity, Buddhism, Hinduism and animism, which is the belief that animals and plants have a spiritual essence. He was working on a study of Jewish practices at the time of his death.

He sought to portray the more extreme elements of religious practices, including Hindu body piercers in India and Christian snake handlers in Alabama.

“I wanted to explore religion not as faith,” Abbas said in a 2011 interview with Singapore’s Straits Times, “but its social, economic impact, and what people do in the name of God.”

Abbas returned to Iran in 1997 for the first time in 17 years, taking new photographs that he included in a 2002 book, “Iran Diary, 1971-2002.” He later visited 16 Muslim countries for a deeper look at the connections between faith and extremism, depicted in his 2009 book, “In Whose Name? The Islamic World after 9/11.”

He described his interest in religion and God as “purely professional.”

“I mean, he doesn’t tell me what to do, how to photograph,” he said on “Fresh Air,” “and I don’t tell him how he should deal with his believers, you know.”

Abbas Attar was born in early 1944 in Iran’s Baluchistan region, bordering Pakistan.

He was 8 when his family moved to Algeria, and he lived through the country’s long war for independence from France.

“I grew up in a situation of violence,” he said in 2011. “But war is not just ‘boom boom.’ I consider that a battle. Wars are a complex phenomenon, not only physical violence, but also psychological, social and emotional. I like to cover the whole span.”

He decided at an early age to become a journalist and, at 18, took up photography, learning by trial and error.

He got his first major break when he was hired by the International Olympic Committee to document Mexico’s preparations for the 1968 Summer Olympics. In 1974, he was in Congo, then called Zaire, to photograph Muhammad Ali before his “Rumble in the Jungle” heavyweight championship fight with George Foreman.

“He was like a film director, and we were working for him,” Abbas said.

Abbas used only his first name throughout his professional career and was deliberately vague about his family background, saying photographers “should stay on one side of the camera.” Little personal information could be learned about him, although Britain’s Telegraph newspaper reported he had four sons.

In 2011, Abbas was asked about the dangers involved in covering wars and revolutions to capture what he called “the exalting and fragile moment.”

‘The shell doesn’t discriminate, does it?” he said. “If I could take pictures without the risk, I would. But I had to be there.”