About 700 of us arrived at the convention center not long after 7pm. We rallied there and marched around the convention center for about an hour. The crowd thinned out a bit and we then broke up into 6 different groups and blocked all of the intersections surrounding the convention center. About 50 of us were at 7th and New York, SE of the building. There were tons of cops behind us, about 5 or 6 cop cars parked with their lights on, and others which blocked off the intersections leading to us. One group from inside the center came out, went to the police complaining that they couldn't get through. The police didn't ask us to move or anything, but they found some other police officer on foot to "escort" his SUV east on Mt. Vernon Pt. The officer walked on the sidewalk yelling "don't get in my way, stay out of my way" and the SUV drove behind him, up onto the sidewalk behind a light pole and about 6" from me (we didn't have the sidewalk blocked, and I was on the end of the chain). We chanted to the police, "The 1% get to drive on the sidewalk! Arrest him!" That incident ended without injury, but it goes to show the police were allowing us to block the street and not even attempting to let cars out by forcibly moving us or even asking us to move.
At around 9:30 an ambulance and fire truck came north on 7th street behind us. As Occupy DC always does when we march, we let the emergency vehicles pass through, and they went to the front of the Convention Center doors on the south side but did not appear to be treating anyone. About 10 minutes later, a silver Lexus came south down 7th street and approached the middle of the human chain. He stopped a couple yards short and slowly started rolling toward the single line of us with our arms locked, without honking or asking us to move (we had previously allowed cars through from obvious locals and people who worked at the Convention Center). He then accelerated into the chain and the protesters armlock broke, two people were brushed by the bumper and jumped to the side and I don't think either of them hit the ground or were injured. A third protester was in between these two and as the car struck him he was flung across the hood, to the passenger side of the car and hit the ground. I wasn't able to see if he caught his fall. I ran after the car and got the license plate number. The cops had the intersection at 7th and Massachusetts blocked off and were standing there as he tried to go through the light. They motioned for him to reverse back down 7th and pull over, and he complied. I can confirm the car is the one shown in this video, and the African American man in the white sweatshirt and ballcap was the driver.
My wife ran down to the ambulance and fire truck that had passed through us before and summoned them. The man who was struck never got to his feet. When I approached him there were about 20 of us around, he seemed quite dazed and wasn't speaking. I didn't see any blood or external wounds. The emergency services began treating him and I saw them prepare a strecher. The AFP attendees began exiting the Convention Center, and one 30ish blonde lady filming with her camera asked me what happened. I said that a car ran over one of the protesters and she said something to the effect of, "Good, you shouldn't be in the street". The paramedics treated the downed protester for at least 20 minutes on the scene and our group then marched south through Chinatown so I didn't see whether he was loaded onto the gurney and taken into the ambulance, but reports are that he was.
As you can see in the video from above, the driver does not appear by his attire to be one of the attendees of the conference. What makes it all the more baffling that he would do this is that there were so many people, cops, and cop cars all around. Really a stupid and mean thing to do.
Update: Thanks for the req list. There has been a vibrant debate in comments about the validity or wisdom of blocking traffic as a means of protest and whether civil disobedience is confined to breaking unjust laws. I can understand both sides of the argument and don't really have a strong opinion.
What I can say is this: Occupy DC does this with every action. The police have given their tacit approval. When we march, we don't get a permit. We don't inform the police of our route. We don't march on sidewalks. We illegally take to the streets, and the police bring their cars in front of us and behind us and block intersections. We chant "Whose streets? Our streets!". When we pass large crowds we ask them to join us, chanting "Off the sidewalks into the streets!". Many do. Nobody has been arrested for taking the streets. The police have not even asked that we don't do it. The general attitude from the authorities has been that first amendment rights of freedom to assemble are more important than traffic laws or the local ordinances which say when you can be in a park. Whether or not this is wise or helpful is up for debate, but it was discussed during an early General Assembly and agreed upon consensus that this was a tactic we would use to draw attention to the movement. For the first week or so, we marched every day at 4:00 pm with the express purpose of jamming up DC traffic during rush hour. This went on for about a week and was discussed at the General Assembly. We decided that this was not a wise course of action and now all actions are planned for specific purposes or causes. And of course, let me just say that when I say "we" I am speaking about what I have seen and not for Occupy DC itself or the movement at large. As I mentioned in the comments, I don't sleep at McPherson and I've only been to a couple General Assemblies, but I participate in almost all of their actions.