Afghanistan: Explosion set off by mistake at arms depot in Kabul

Kabul, Afghanistan -- An explosion that took place in the arms depot of the Afghan National Directorate of Security in Kabul on Thursday was set off by mistake, authorities said.

The blast was not a terrorist attack and there were no casualties, Interior Ministry spokesman Siddiq Siddiqui told CNN.

The NATO-led International Security Assistance Force in Afghanistan tweeted that its headquarters is "all clear" and "resuming normal operations."