Hassan Rahimi recalls the last time he saw Farzana and Atta, his twin daughter and son.
He had just ended a grueling shift at a local bakery. It was around noon when he arrived at the family's cramped, one-room home in Dasht-e Barchi, a poor neighborhood in the Afghan capital. His wife was working over a portable stove, boiling lentils. Farzana and Atta were agitated. They did not want to be late for class.
"I urged them to eat lunch before leaving," Rahimi says, his soft voice breaking. "They drank some leftover tea and took a few bites of bread. They left with their bags slung over their shoulders. 'Goodbye, Dad.' That's the last thing they said to me."
Just a few hours later, Rahimi learned via telephone that his 19-year-old twins were dead.
They were among the 34 high-school graduates who were killed when a suicide bomber entered their packed classroom at the nearby Mawoud Academy and detonated his explosives.
All the dead were under the age of 20. The students, including the 56 who were wounded, were attending extra lessons to prepare for university entrance exams that were just weeks away.
"They were both so excited to take their exams," Rahimi says. "They would be up until 2 a.m. every night studying. I would plead with them to sleep, but they wouldn't listen."
Rahimi says he fell to his knees on the concrete floor of their home, overcome by grief. Loss soon gave way to anger.
"My children weren't fighting in a war; they were students who had gone there to study," Rahimi tells RFE/RL via telephone, as the wails of children and women echo in the background. "What crime had they committed to deserve such a horrific death?"
The blast that killed the twins was claimed by the militant group Islamic State (IS). It was the latest IS attack to target members of Afghanistan's minority ethnic Hazaras -- a Shi'ite community that has in the past been targeted by similar large-scale attacks.
It was also the latest attack to target Afghanistan's education sector. At least 86 others have been destroyed by militant attacks this year alone, according to UN data, and more than 1,000 schools across Afghanistan remain closed for security reasons.
"We no longer have any expectations of the government," Rahimi says, a reference to disillusionment with the administration of President Ashraf Ghani, which has struggled to curb mass unemployment and escalating violence plaguing the country.
The Rahimi family moved to Kabul almost 10 years ago from their village in the southeastern province of Ghazni, a Taliban stronghold.
"There weren't any schools in our area," says Rahimi, who has three other children. "There wasn't any development and [there were] no jobs. We left so that my children could have a brighter future."
Farzana and Atta were the first in the family to finish school. Rahimi, a laborer in Ghazni, and his wife only studied the first few years of elementary school.
Life for the Rahimi family was difficult in the Afghan capital, an overcrowded city of 4 million people at risk of near-constant militant attacks and mass unemployment. The family rented a room in their predominately Hazara neighborhood in western Kabul where running water and electricity worked only sporadically.
But for Rahimi, the sacrifice would almost certainly be worth it -- his children would have a better life.
Farzana and Atta had big dreams.
"Farzana was always saying she wanted to be a teacher and give back to her country," he recalls. "Atta was writing articles for a news agency and wanted to become a lawyer. He was interested in social and cultural issues."
"It's an unbearable loss for us," Rahimi says. "But these children who were killed, including my own, were the future of the country. They are also Afghanistan's loss. They were the next generation of doctors, engineers, and teachers."
Atta, who worked for the Farhang news agency, became the 12th reporter killed in Afghanistan this year -- the "bloodiest reporting period" ever for journalists in that country, the Afghan Journalists Safety Committee, a local watchdog, said.
Farzana and Atta were buried in a funeral service atop a dusty hill in Kabul on August 16, their wooden caskets lined next to dozens of others.
When Rahimi went to the hospital morgue to identify his children, he says, he could barely recognize them.
"Their bodies were shattered," Rahimi says, pausing for a moment before continuing, "Their faces had been disfigured beyond recognition. I recognized them only because of the clothes they were wearing."
The twins had been inseparable since birth. They were born only 15 minutes apart and spent most of their short lives together. "They were best friends," Rahimi says. "They laughed, cried, and dreamed together."
They were also hunched over the same desk, studying to carve out a brighter future, when they were killed together.