And this from NBC producer Ali Arouzi in Teheran:

Initially, it was a peaceful demonstration. People were forming a human chain, saying they wanted their vote back… but the more the police came, the angrier the mob got. It became sort of a mob mentality here. Now the police have swelled in huge numbers. They are being very, very violent with the crowds.

Every young person I’ve spoken to here, I’ve asked them, “do you think you coming out onto the streets is going to make a change?” They said, no, but we have to come out anyway if we want our voices to be heard, but they’re sure this won’t make a change.

Demonstrators have been injured. People have come up to us and they’ve shown us that their arms have been bruised, black eyes, broken noses, bloody heads. But they are fighting back as well. This is, I mean, I’ve been in Iran four years here and everything here has always been contained. Today we saw the demonstrators setting on the police. An hour ago, maybe 30, 40 demonstrators rushed the police, throwing stones at them. One of the policemen fell and they were kicking him in the head and some of his colleagues had to come and drag him away.

[Source.]