A young Iranian woman who fell into a coma after being arrested by Tehran’s notorious morality police died on Friday, state media and her family said. Activists called for those responsible for her “suspicious” death to be brought to justice.

Mahsa Amini, 22, was visiting the Iranian capital with her family when she was arrested by the police unit responsible for enforcing the Islamic Republic’s strict dress code for women, which includes compulsory wearing of the headscarf in public.

“Unfortunately, she died and her body was transferred to the coroner’s office,” Iranian state television reported.

Persian-language media, including website Iran Wire and newspaper Shargh, have quoted her family as saying that she was hospitalized in a coma hours after her arrest this week and has now died.

It is not yet clear what happened between her arrival at the police station and her departure to the hospital. The broadcaster 1500tavsir, which monitors human rights abuses in Iran, said she suffered a blow to the head.

Images posted to social media showed crowds gathering outside the hospital where she was being treated and police trying to disperse the dozens who had gathered.

“The circumstances leading to the suspected death in custody of 22-year-old young woman Mahsa Amini, including allegations of torture and other ill-treatment in custody, warrant a criminal investigation,” Amnesty International said.

“The so-called ‘morality police’ in Tehran arbitrarily arrested her three days before her death while enforcing the country’s abusive, degrading and discriminatory laws on compulsory veils. All agents and officials responsible must be brought to justice,” she added.

On Twitter, prominent Iranian lawyer Saeed Dehghan described Amini’s death as “murder” and said she suffered a blow to the head that fractured the base of her skull.

State television broadcast images on Friday that allegedly show her falling to the ground in a large hall full of women while arguing with one of the instructors about her clothes.

In a statement on Friday, Tehran police insisted there had been “no physical encounter” between officers and Amini.

Amini was among a number of women who were taken to a police station for “dress code briefing” on Tuesday.

“She suddenly passed out while in the hall with other visitors,” the statement said.

Earlier, President Ebrahim Raisi had instructed the Home Secretary to launch an investigation into Amini’s case.

Several lawmakers said they would raise the case in Parliament, while the judiciary said it would form a special task force to investigate.

The head of the New York-based Center for Human Rights in Iran, Hadi Ghaemi, called her death an “avoidable tragedy”.

“The government in Iran is responsible for this. She was arrested under cover of the state’s discriminatory compulsory hijab law and died in state custody,” he said.

Amini’s death comes amid growing controversy both inside and outside Iran over the behavior of the morality police, officially known as the Gasht-e Ershad (Command Patrol).

In July, video circulated on social media of a woman standing in front of a police van asking for her daughter’s release.

The veiled woman held the van as it started and was only thrown away when it picked up speed.

Also in July, a young Iranian woman, Sepideh Rashno, disappeared after she got into an argument on a Tehran bus with another woman, who accused her of taking off her headscarf.

She was held by the Revolutionary Guards and appeared on television in what activists said was a forced confession before being released on bail in late August.

Activists accuse Iran of being in the midst of a major crackdown affecting all sectors of society, including a new crackdown on the Baha’i religious minority, death sentences for gays, a spate of executions and arrests of foreigners.

Raisi plans to travel to the UN General Assembly in New York next month, where he will face an intense scrutiny of Iran’s human rights record.