Nytimes.com | By Jane Arraf and Farnaz Fassihi

The protests that have swept Iran following the death of a woman in police custody have been especially intense in the country’s minority Kurdish population.

ERBIL, Iraq — The protests that have thrust Iran into turmoil since the death of a young woman in police custody have been striking for the way they have cut across ethnic and social class divides, but there is one group that has risen up with particular fury.

The woman who died after being swept up by Iran’s notorious morality police was a member of Iran’s Kurdish minority, which has long suffered discrimination, and the group’s rage in recent days reflects its longstanding grievances.

“This is not all about the head scarf,” said Hana Yazdanpana, a spokeswoman for the Kurdistan Freedom Party, an Iranian paramilitary group based in Iraq. “The Kurds want freedom.”

The protests have been especially intense in northwest Iran, where Kurds, who make up about 10 percent of the Iranian population, are concentrated. On Sunday, Iranian troops appeared to have retaken a Kurdish city in the region, Oshnavieh, that had been briefly seized by protesters.

The catalyst for the protests was the death of Mahsa Amini, 22, who died on Sept. 16, three days after she was arrested in the capital, Tehran, by the morality police, accused of violating the country’s strict codes on modest dress for women.

Ms. Amini’s story drew protests from Iranians furious not only over the treatment of women under the country’s conservative clerical rulers, but also over a host of other issues, including an economy crippled by years of sanctions, the pandemic, corruption and repression.

The protests began with Ms. Amini’s burial nine days ago in her hometown, Saqhez, in the northwest and then, fueled by social media, quickly spread to the rest of the country.

Since then, at least 50 people have been killed and hundreds more injured or arrested, rights groups say. They believe the death toll is likely higher. In Kurdish regions, 17 people were shot dead, including four children, according to the Hengaw Human Rights Association and Kurdistan Human Rights.

The Iranian authorities claimed that Ms. Amini had died of a heart attack. But her father, Amjad Amini, told BBC Persian service last week that he believed she had been beaten in custody, and he said he had been prevented from viewing the autopsy report. He has not been heard from since.

The unrest is the most significant outpouring of anger over theocratic rule in the country since the 2009 Green Movement. In dozens of cities, protesters have been heard chanting, “Women, life and freedom” and “Death to the dictator,” deriding one of the government’s most fundamental and divisive symbols, the ailing supreme leader, Ayatollah Ali Khamenei.

In social media videos that have captured widespread attention, women can be seen ripping off their head scarves and burning them in the street. The government has responded with deadly force and by blocking internet across the country.

The confrontations over the weekend in Oshnavieh, which is mostly Kurdish, signaled not just the level of rage among many Iranians, but also the determination of the government to quell the protest.

From Friday evening into Saturday, protesters there flooded the streets, some throwing firebombs and stones at security forces, setting fires and overturning police cars. At least some security forces withdrew from the city, according to multiple Kurdish sources.

But on Sunday, Iranian security forces moved to re-establish control over Oshnavieh, according to Ms. Yazdanpana, the Kurdistan Freedom Party spokeswoman, whose group has members in the city. A Kurdish activist in touch with residents of the city said the security forces had returned to areas of the town they had vacated.

Ms. Yazdanpana said members of Iran’s powerful Islamic Revolutionary Guard Corps armed with machine guns and backed by artillery on the outskirts of town were operating in Oshnavieh on Sunday. Some went door to door making arrests, she said.

“They are moving forward,” she said.

But many protesters were refusing to leave the streets, Ms. Yazdanpana said. “The people do not want to go home,” she said. “They are trying to send their voice to the world.”

In the nearby town of Balo, protesters burned the houses of Revolutionary Guard members on Thursday, and the Guards withdrew from parts of the town after clashes that killed at least two protesters, according to Rebin Rahmani, director of the Kurdistan Human Rights Network. But they were replaced by anti-riot forces, he said.

A resident of Balo reached by phone said that in addition to the two dead, several young men had been seriously wounded, with their families forbidden to visit them in the hospital. He said Basij fighters, members of the Revolutionary Guard, were carrying out arrests but keeping a low profile because they did not want to risk retaliation. The resident insisted on being identified only by his first name, Youssef, out of fear of security forces.

Kurds in Iran, Iraq, Turkey and Syria, although politically divided, form what is generally considered the largest contiguous ethnic group in the world without an independent state.

“We salute the uprising,” said Mazloum Abdi, security leader of the Kurdish-led region of northeastern Syria, which broke away from Syrian government rule in 2013.

In Iraq, the former president of the Kurdistan region, Massoud Barzani, called Ms. Amini’s family last week to express his condolences, saying he hoped justice wold be served. The region, aided by the help of a U.S.-led no-fly zone, broke away from Iraqi government control after 1991, establishing the semiautonomous region, which is recognized by the United Nations and the United States.

On Saturday, Iran launched a cross-border attack into that region. The Revolutionary Guards said they were targeting “terrorist and anti-revolutionary groups,” referring to Iranian Kurdish opposition forces based there.

Analysts said that despite Mr. Barzani’s unusually outspoken statement regarding Iran, the Kurdistan Region was unlikely to enter the fray in support of Iranian Kurds.

In Iran on Sunday, as the protests continued, student unions at two universities issued a statement saying that campus security officers had kidnapped at least 20 students at gunpoint. A national teachers’ union committee called for teachers and students to strike on Monday and Wednesday in protest.

But some protesters were paying a heavy price.

Videos posted on social media showed the police dragging one woman by the hair, banging the head of another onto a street curb, shoving a man into the trunk of a police car and firing bullets into crowds.

The protesters appeared to be receiving increasing support.

Public figures in Iran — including athletes, writers and musicians — have issued statements of solidarity. A national fencing team captain, Mojtaba Abedini, resigned in support of the protesters. Even an author close to the government, Mostafa Mostour, criticized the violence being used to suppress the uprising.

“Our women are only asking to live a normal and ordinary life,” he said.

Jane Arraf reported from Erbil, Iraq, and Farnaz Fassihi from New York. Sangar Khaleel contributed reporting from Erbil.