A few minutes later, when an anti-terrror unit arrived on the scene, all that was left to do was to ensure there were no other terrorists lurking - and survey the terrible scene. Four men lay dead and seven others were wounded after the men from the south-east Jerusalem village of Jabel Mukaber had finished hacking and shooting their way through the crowded shul with meat-cleavers, knives and a pistol.
The time that elapsed until properly equipped forces arrived was not the result of a tactical failure on the part of the police, but simply the impossibility of foreseeing where the next attack will occur. Jerusalem has a million residents, and plenty of potential assailants, often people with no known affiliation with terror groups.
Like the Abu Jamal cousins, nearly all the recent terror attacks in Jerusalem were by Jerusalem residents who, in many cases, knew the location of their victims well.
While the Abu Jamal family is known to have had contacts with the Popular Front for the Liberation of Palestine, which endorsed the massacre (as did Hamas), the Shin Bet is not aware that they had any organisational support for their attack.
The attack was largely a surprise, as the police had taken the view that the period of tension in Jerusalem was drawing to a close. Commissioner Yochanan Danino had even spoken on Thursday about how his officers were "restoring the calm" to the capital. Friday's Muslim prayers on Temple Mount, which followed a meeting in Amman between Prime Minister Benjamin Netanyahu, King Abdullah and US State Secretary John Kerry, passed without unrest.
This leaves Israel's leaders and security establishment without any clear responses besides continuing to reinforce the police presence in the capital.
Unlike the Second Intifada when the suicide bombers were sent from the West Bank, there is no "terror infrastructure" to eliminate.
Some politicians have called for the army to be sent into Palestinian areas of East Jerusalem. Other responses being discussed include easing gun regulations to allow more members of the public to carry weapons.
