More on the Karbala attack - US soldiers were captured alive

I've been watching for details on this highly unusual attack in Karbala (1, 2, 3), and I'd read a rumor to this effect, but hadn't lent it creedence. Now AP is picking up that story, adding more detail.

Contrary to public statements by the U.S. military, four U.S. soldiers did not die repelling a sneak attack at the governor's office in the Shiite holy city of Karbala last week. New information obtained by The Associated Press shows they were abducted and found dead or dying as far as 25 miles away.

The brazen assault, 50 miles south of Baghdad on Jan. 20, was conducted by nine to 12 militants posing as an American security team.....

One Iraqi official said the leader of the assault team was blond, but no other official confirmed that.....

The U.S. accounts did not say where the soldiers were killed. Iraqi officials said the four were captured alive and shot just before the vehicles were abandoned.

There's more detail in the article if you're interested. Supposedly four suspects have been detained.

Two hours later: American officials confirm, offering their (second) version of what happened in Karbala.

Within hours of the AP report that four of the five dead soldiers had been abducted and found dead or dying about 25 miles to the east of Karbala, the military issued a long account of what took place.

A few more details, but still no information who was behind this.

(I discount the growing rumor that these were Iranians, because thus far, the Iranians have been very judicious in their actions.)