Moments ago, MSNBC broadcast images of flag-waving protesters in Arsenal Park in Pittsburgh amidst a cloud of what appeared to be tear gas.

Some of the protesters were shown pouring water into their eyes -- apparently to rinse the gas out. MSNBC reported that as many as 15 protesters have been arrested.

Though it was unclear who had released the tear gas, earlier today AFP quoted a spokesman for the Pittsburgh G20 Resistance Project as saying, "the city has bought a thousand canisters of tear gas. That's something people are concerned about, like what to do if they're gassed."

Though an MSNBC's Norah O'Donnell declared that "chaos erupted" and that "it was quite a scene" with car alarms going off, hundreds of protesters and police in riot gear, it still didn't appear to be as large or chaotic as past G20 protests.

World leaders -- including President Obama -- are expected in Pittsburgh today, though MSNBC reported that the protesters are being kept far away from the actual summit.

Late Update: Showing video of the protests that CNN's Wolf Blitzer called "raw" and "unedited," CNN reported that its own Brian Todd was apparently tear gassed. Before that happened, a robotic police voice told everyone -- journalists included -- to disperse from what was "an unlawful assembly."

"It got very hard to breathe," Todd said of the gassing. "And it just kind of crept into your lungs and also into your throat."

Then Todd's technician poured water over his face. "It was a great relief," the journalist said.