the security checkpoint at the palestine and sheraton hotels, home to western journalists and one of the most fortified compounds in baghdad. it's also where carl was heading for a meeting. >> there was a car that was behind us. and the car that was behind us swerved from behind us and kept going down that road and headed straight for that checkpoint. and that was the second suicide bomber. and we were actually about to drive right into that. >> seconds later, the car that passes them explodes. >> it felt like the bomb came from underneath the floorboards. i said to myself, i can't believe we're about to die. i said, i -- i was just angry, and i was just incredulous, so to speak. and the tree that we were underneath was on fire. >> but the attack isn't over. and the biggest explosion is yet to come. manning a machine gun at the checkpoint is specialist darrell green. >> at that time, they -- the cement mixer was trying to come through our perimeter. >> a huge cement mixer filled with...