Police attacked this person because:

[Riot]

Irony alert:

State Department spokeswoman Victoria Nuland said that the United States supported the right to peaceful protest in Russia as it does "anywhere in the world."

"We expect that those demonstrations will remain peaceful on behalf of all parties, whether they're the demonstrators or whether they are those keeping social order," she said.

"So our expectation is that if there are protests, that they will be peaceful and that they will be allowed to proceed peacefully," Nuland said.

# UPDATE: Twitter is reportedly blocked in Egypt itself right now, however. More details on that here. UPDATE 2: There are workarounds, however.
# Looking for live video? You can watch Al Jazeera English live on the web. Better, perhaps, is the video feed from cairowitness, who has set up a webcam downtown in Cairo, Egypt's bustling capital. (UPDATE: That video feed is down.) Hillary Clinton just spoke. Highlights: US "very concerned" about the crackdown, protesters should refrain from violence. We support universal human rights, urges Egyptian government to allow peaceful protests and reverse cutoff of communications.