At the time of the incident, a group of 2,000 religious scholars or clerics had gathered at the university to issue a fatwa against suicide attacks in the on-going war in Afghanistan, reports a news agency.
Kabul police confirmed that it was a suicide bombing.
“The suicide attack happened outside the (Loya Jirga) tent when religious scholars were leaving the gathering,” Kabul Police spokesman Hashmat Stanikzai was quoted as saying.
Prior to the incident, the clerics had announced that the Afghan war is “illegitimate and has no roots in the Sharia law”.
Taliban has denied any involvement in the attack.