Photographer shot by Oakland Police with "less-lethal" round, for no apparent reason

An Oakland Police Department officer shot blogger and videographer Scott Campbell with a projectile (a "bean bag" round or rubbber bullet, it's not clear which) while he was recording video during Occupy protests this weekend. Mr. Campbell was not threatening the officers or engaged in any violent activity that required this response. Is it legal for police to shoot photographers in a public place simply because they do not want to be photographed? [Video Link]