Picture from the AP
Taliban or associated terrorists attacked an army recruitment center and a bus load of officers driving to work. Both attacks included a combination of small arms attacks and suicide bombers which have been hallmarks of attacks on large facilities recently. What these groups do is use small arms cover to get the suicide bombers close to their targets then the bomber detonate then as reinforcements arrive and begin to overwhelm the attacks they detonate their belts or vests.
The Haqqani network has been responsible for a large number of the major attacks in Kabul and it would not be surprising to find out they were behind this one as well. The Haqqanis have been subject to an intense drone campaign the last three months in their strong hold around Miran Shah and Datta Khel in North Waziristan also ISAF forces have been making a push against Haqqani forces inside of Afghanistan. It would stand to reason they would push back hard. This attack may have been planned to coincide Chancellor Merkel's visit to the German troops stationed in Afghanistan.