For children, the risk of violence has become a grim part of getting an education. "He was a smart and energetic boy, top of his class", Assadullah said. It was not clear how many students were at the centre at the time of the attack.
Majroh didn't say if all the victims were students and whether any of their teachers were also among the casualties.
The Afghan authorities have revised the death toll from the previous day's horrific suicide bombing in a Shite area of Kabul to 34 killed, not 48.
Most of the victims of the bombing are underage teenagers who were in the classroom on preparation for University admission.
The attack came less than two weeks after almost 40 people were killed and dozens more injured in a bombing and shooting attack on Shiite worshippers in eastern Afghanistan near Pakistan's border. The attack was blamed on the ISIS terror group.
More than 1,000 schools across Afghanistan remain closed for security reasons and at least 86 have been destroyed by militant attacks this year alone, according to United Nations figures.
Nahida Rahimi, a doctor at Kabul's Isteqlal Hospital, where some of the wounded are being treated, said a mother told her she had lost a son in Wednesday's bombing after already losing another a year earlier in another suicide bombing, also in Kabul, that targeted Shiites. He warned the toll could rise.
Gunmen attacked military training centre in Qala-e-Wazir in Kabul city on Thursday, reported Tolo News. The casualties were taken to a hospital.
Also Wednesday, six children were killed when they tinkered with an unexploded rocket shell, causing it to blow up, said Sarhadi Zwak, spokesman for the governor of the eastern Laghman province.
"Death and hatred to this government and filthy terrorist that everyday they are killing innocent Afghans", he added.
Afghanistan is littered with unexploded ordnance left by decades of war.
A week into the offensive, however, Afghan forces were still busy clearing areas around the city and along the highway in the province, where rebels were still fighting with the security forces.
At least nine security forces were still missing and four others were wounded in the attack, said Abdul Hai Nemati, the governor of Baghlan. "Today, even in Kabul, people may be starting to fear a sudden attack by the Taliban against the city". The fighting continued for five days with more than 100 members of the Afghan National Security forces killed and 20 civilians.
"At around 4 pm this afternoon, a suicide attacker who had strapped explosives to his body detonated himself inside the Mawoud education centre", police spokesman Hashmat Stanikzai said.
As clearing operations continued, analysts said the Taliban demonstrated considerable strength ahead of possible peace talks, while highlighting the difficulty Afghan forces have in confronting the insurgents, especially in urban areas - even with the backing of USA air power.
The Taliban launched a co-ordinated offensive last Friday, overwhelming the city's defences and capturing several neighbourhoods.