A suicide bomber attacked an education centre in the Afghan capital on Friday where hundreds of students were preparing for university exams, killing at least 20 people, most of them young women.

According to the police and witnesses, as reported by BBC, nearly 30 others were wounded in the school located in the Dasht-e-Barchi area where they were sitting for a practice university examination.

While no terrorist group has claimed responsibility for the attack, it was reported that many of the areas are minority Hazaras, who have been targeted by Islamic State (IS) militants and the Taliban.

Hazaras are Shia Muslims and Afghanistan’s third largest ethnic group.

“Students were preparing for an exam when a suicide bomber struck at this educational centre. Unfortunately, 19 people have been martyred and 27 others wounded,” Kabul police spokesman Khalid Zadran said.

A student of the school, Akbar said most of the victims were girls. “We were around 600 in the classroom. But most of the casualties are among the girls,” Akbar said.

Relatives and friends flooded hospitals to look for their family members who are victims of the attacks.

The bomber shot dead two security guards before entering the gender-segregated classroom, student Ali Irfani, who escaped the carnage, told AFP.

“Not many boys were hit because they were at the rear end of the classroom. The bomber entered from the front door where girls were sitting,” he said.

A resident who ferried victims to hospitals said he saw body parts scattered across the floor of the hall.

“Many students were hit by shrapnel in their head, neck and eyes,” said Asadullah Jahangir.

Kabul police spokesman Khalid Zadran said 20 people were killed and 27 others wounded.

The United Nations Assistance Mission in Afghanistan (UNAMA) told AFP that at least 24 people were killed and 36 others wounded in the attack, adding the numbers were expected to rise.

A shopkeeper from the neighbourhood said there was a loud explosion and then crowds of students rushed out of the centre.

“It was chaos as many students, boys and girls, tried to escape from the building. It was a horrific scene. Everyone was so scared,” he told AFP, requesting anonymity.

Italian NGO Emergency, which operates a hospital in Kabul, said it had received 22 patients, including 20 women, two of whom had died.

“The victims are all between 18 and 25 years old, and most of them were in the classroom to take an exam,” it said in a statement.