Dozens of women from Afghanistan’s Hazara minority protested in the capital on Saturday after a suicide bombing killed 20 people – mostly young women from the ethnic group – a day earlier.

A bomber blew itself up in a Kabul study hall on Friday as hundreds of students in the Dasht-e-Barchi district took tests in preparation for university entrance exams.

The western neighborhood is a predominantly Shia Muslim enclave and home to the minority Hazara community – a historically oppressed group that has been the target of some of Afghanistan’s most brutal attacks in recent years.

Police said at least 20 people were killed, but the United Nations has put the number at 24.

On Saturday, about 50 women chanted “stop the Hazara genocide, it is not a crime to be Shia” as they marched past a hospital in Dasht-e-Barchi where several victims of the attack were being treated.

Dressed in black hijabs and headscarves, angry protesters carried banners that read: “Stop killing Hazaras,” an AFP correspondent reported.

Witnesses told the AFP news agency that the suicide bomber detonated in the women’s section of the gender-segregated hall.

“Yesterday’s attack was aimed at the Hazaras and Hazara girls,” protester Farzana Ahmadi, 19, told AFP.

“We demand an end to this genocide. We staged the protest to demand our rights.”

Demonstrators later gathered outside the hospital and chanted slogans while dozens of heavily armed Taliban, some carrying rocket-propelled grenade launchers, stood guard.

Since the hard-line Taliban returned to power last August, protests by women have become risky as scores of protesters were arrested and rallies were dispersed by Taliban troops who fired shots in the air.

No group has claimed responsibility for Friday’s attack on the Kaaj Higher Educational Center.

But the jihadist group Islamic State (IS) considers Shia heretics and has previously claimed attacks on girls, schools and mosques in the area.

The Taliban also view the Hazara community as pagans, and human rights groups have often accused the Islamists of targeting them during their 20-year insurgency against the former US-backed government.

Since returning to power, the Taliban have pledged to protect minorities and address security threats.

However, human rights group Amnesty International said Friday’s attack was “a shamed reminder of the inability and utter failure of the Taliban as de facto authorities to protect the people of Afghanistan”.

In May last year, before the Taliban returned to power, at least 85 people – mostly girls – were killed and around 300 injured when three bombs went off near their school in Dasht-e-Barchi.

Neither group claimed responsibility again, but a year earlier, IS claimed a suicide attack on an education center in the same area that killed 24 people.

ISIS has emerged as a key security challenge for the Taliban, but officials claim their forces have defeated the jihadists.