From AP, May 28:

A suicide car bomber struck a busy Baghdad commercial district Monday, killing at least 21 people, setting vehicles on fire and damaging a nearby Sunni shrine, police and hospital officials said.

The blast went off at 2 p.m. in the Sinak market area on the east side of the Tigris River, just as U.S. and Iranian diplomats were wrapping up a historic meeting aimed at ending the violence wracking the country.

Insurgents carried out several mortar and car bombing attacks throughout the capital Monday and even waged a lengthy gunbattle with police in broad daylight. The wave of violence, which killed 36 people across Baghdad, came despite a nearly 15-week-old U.S.-led security crackdown in the city.

Another 33 bullet-riddled bodies were found handcuffed, blindfolded and showing signs of torture in different parts of Baghdad, the apparent victims of ongoing sectarian violence.

The deadliest attack Monday was the car bombing in the Sinak district, near the Abdul-Qadir al-Gailani mosque.

AP Television News footage showed dozens of astonished people wandering among the scorched cars and debris that littered the scene. Firefighters in yellow helmets struggled to extinguish the fire as ambulances rushed to evacuate the wounded.

Ghaith Karim, a 38-year-old Shiite cloth merchant, was heading to a nearby bus station when he saw a fireball and heard the blast.

"It was tremendous. I felt the ground was shaking," he said. "When I reached the scene, I found legs, charred pieces of bodies and pools of blood. Casualties were being evacuated by civilian cars."

The television footage showed damage to the mosque's minaret, while the cleric in charge of the Sunni shrine, Mahmoud al-Issawi, said the blast damaged the building's dome as well.

"The enemies of Iraq are the only ones who benefit from this bombing. These enemies have targeted our homeland, religion and our brotherhood," al-Issawi told Iraqiya TV.

So who is behind the Sinak market bombing? Was it Sunni jihadists, and the Abdul-Qadir al-Gailani mosque was unintentional "collatoral damage"? Or have Shi'ite militants adopted the heretofore Sunni tactic of suicide bombing, and the mosque was the target? Or was it another blow in the Sunni civil war? Or is are these attacks the work of deep-cover Pentagon or CIA units, as has been endlessly speculated?

See our last posts on Iraq and the insurgency.