Holy crap...

This could be the spark that sets off the long threatening civil war that's been percolating for a couple of years now in Iraq:

In Iraq, bombing sparks fears of more violence

Today's bombing of a Shiite shrine in Samarra, Iraq, has renewed fears of an escalation in violence between the country's Sunni and Shiite Muslim communities. Protests erupted in Samarra (photo) and elsewhere around Iraq, while some Shiite leaders appealed for calm while others promised retribution. President Bush has condemned the bombing and urged Iraqis to "exercise restraint" in responding to it. Here's a roundup of the latest news:

and...

Update at 5:55 p.m.ET: Three imams were killed as Shiite gunmen attacked 27 Sunni mosques.

- Al Jazeera reports that Shiite leaders in Baghdad's Sadr City neighborhood "called for demonstrations against the blast." The Arab network also gives this background on the shrine that was attacked: "The shrine contains the tombs of two revered (Shiite) imams, both descendants of the prophet Mohammed. ... An attack at such an important religious shrine would constitute a grave assault" on Shiites.

And more here.