Getty has photos. Few details as of yet: it was a truck, it went off outside the entrance to the market at around 5 p.m., when people were shopping for dinner, and afterwards they used pick-up trucks to help evacuate the wounded to the local hospitals, which were soon in chaos.

It’s the latest episode in a jihadi surge that began with the double bombing at the university bus stop in Baghdad two weeks ago. Why the escalation? Says the AP, probably correctly:

No group claimed responsibility for the attack, but it appeared to be part of a bid by Sunni insurgents to provoke retaliatory violence and kill as many people as possible ahead of a planned U.S.-Iraqi security sweep.

Why would Sunni jihadis want to goad the Sadrists into a heavy handed response? Two reasons. First, it’ll draw in more jihadis from the surrounding Sunni countries. And second, it’ll make the Sadrists big fat targets for a certain local army:

Ironically, the Americans’ greatest hope for success in defeating the Shi’ite militia may be the Sunni insurgency. Despite token attempts at national reconciliation, they are not part of the political process, do not negotiate meaningfully with the government, and are under no illusions about what a “troop surge” means for them. In recent weeks they’ve faced U.S. air strikes and Iraqi Army raids in downtown Baghdad. And the insurgents have continued to rain terror down on mostly Shi’ite civilian concentrations, in market places, universities and religious gatherings.

So, while Sadr may be able to cut deals with the Americans, Shi’ites in Baghdad and elsewhere face escalating terror attacks from the insurgency. If violence directed against Shi’ites demands a more public show of force by the Mehdi Army, it may be forced to break cover and risk becoming targets of U.S. firepower.

Iraqpundit says the security crackdown is set to begin in earnest on Monday. According to Peter Pace, the Iraqi army units involved are currently operating at about 60% manpower.

Eight car bombs went off today in Kirkuk, the oil-rich Kurdish holy city in the north. The Kurds have so many enemies it’s not even worth guessing who might have been behind it. Thankfully, only two were killed. And another American helicopter has been shot down, leading the crack dKos strategy team to lament the fact that fighting AQ has helped them to “perfect their methods.” When will Chimpy learn to take the path of least resistance?