The BBC Paul Wood:
How many civilians have been killed - people who either have not left through choice or have been unable to leave - is the crucial question.
I suspect we will have to wait for a definitive answer until the smoke has literally cleared.
As an embedded reporter, I see literally what the military sees.
It is not particularly that the marines want to censor me but I am stuck with one unit and that is all I can see.
When we went through south of the main road last night, the streets - no surprise here - were absolutely deserted, the shops were shuttered.
One can only imagine the plight of the civilians.
I have questioned many times senior officers here about the use of heavy weapons because they have been using 155mm artillery in Falluja, they have been dropping 2,000 pound bombs.
The bullets that they fire are high velocity. The buildings are of poor construction here - the bullets travel through the walls.
And when they see what they believe to be militants - and these marines are incredibly calm under fire, they are almost unflinching - they do wait until they see a guy with a gun but when they see that, they open up with everything they have got and the question is, how much collateral damage is there going to be?
At the moment we simply do not know.
Posted by bushmeister0 at 10:08 PM EST