Yep. Read this story.
An account from the comments section of that story:
I was there! Just taking pics, but I decided to gtfo when somebody yelled gas
and I saw a cop holding said gas cannister.
Basicly the protesters went into the street in front of the City & County building and the cops wern't keen on it, so they started lining up and telling
everyone to get back on the sidewalk, at which point somebody hit the deck in
the street (pepper spray perhaps?) and a mob sort of formed from there. It was
about that point that I whipped out my camera and at the same time my boyfriend
and I both got shoved by a couple of riot cops for doing nothing more than
standing there. We would have moved if they said so, but you know Denver cops,
violence for no real reason. From there the protesters bolted across the park,
past the Seal Fountain, across Colfax and started heading down 15th. Some kid
pulled one of the road closed signs into the middle of the intersection of 15th
and Colfax and the mob made it about a block or two before the cops cut them off
and they sort of got cornered against a building. It was soon after that I heard
somebody yell gas and to run, so I joined a small herd of people in running
cause getting pics is one thing, getting gassed...not so keen on it.
I was on the Mall Shuttle, heading down to Wyknoop where the "Big Tent" is located. Many powerbloggers like Kos, Greenwald, the crew from FireDogLake and so forth are down there and I wanted to see if I could catch any of them. Well, the Shuttle stopped and there was this huge ruckus.
Police officials asked RTD to shut the 16th Street Mall bus shuttle service
shortly after 7 p.m., said RTD spokesman Scott Reed. The mall service resumed
around 9:30 p.m