WTF?

I haven't addressed this yet because various fuzzy versions have been floating around, but the basic storyline seems to have solidified:

BAGHDAD, Iraq (CNN) -- A British armored vehicle escorted by a tank crashed into a detention center Monday in Basra and rescued two undercover troops held by police, an Iraqi Interior Ministry official told CNN.

...

In a statement released in London, Reid did not say why the two had been taken into custody. But the Iraqi official, who spoke to CNN on condition of anonymity, said their arrests stemmed from an incident earlier in the day.

The official said two unknown gunmen in full Arabic dress began firing on civilians in central Basra, wounding several, including a traffic police officer. There were no fatalities, the official said.

The two gunmen fled the scene but were captured and taken in for questioning, admitting they were British marines carrying out a "special security task," the official said.