A Pennsylvania National Guardsman stands watch on the West End Bridge early Thursday morning.
Supporters of a free Tibet march through Oakland.
A demonstrator for a free Tibet marches through Oakland.
Protesters avoid the pepper gas fired by police in Lawrenceville during their march.
A U.S. Coast Guard boat heads up the Monongahela River beneath the Smithfield Street Bridge Thursday morning.
Supporters for a free Tibet hold signs as they march through Oakland.
Police stand in a smoke cloud from a smoke bomb after a clash with protesters along Baum Boulevard during a march by demonstrators on Thursday.
Police arrest a protester near Baum Boulevard during a march by demonstrators on Thursday.
Police arrest a protester near Baum Boulevard.
Supporters of a free Tibet march along Forbes Avenue in Oakland on Thursday.
Police stand watch along Liberty Avenue near the Iron City Brewery near Lawrenceville during a march by demonstrators on Thursday.
Protesters push a dumpster at police down Liberty Avenue in Lawrenceville.
A protester with his face concealed stands in the crowded streets of Lawrenceville during a protest march on Thursday.
A protester runs through gas after police fired several canisters at the protesters in Lawrenceville.
A protester dressed as a cow taunts police in Lawrenceville.
Adele Meyer, 20, of Bloomfield skips in front of Police officers along Liberty Avenue as they move towards a large group of protesters.
A protester cheers as he marches through Bloomfield on Thursday.
Police take a defensive posture as they fire tear gas and shoot beanbag bullets at protesters along Baum Boulevard.
Police line up to fire non-lethal ammunition at protesters along Baum Boulevard during a march on Thursday.
Police form a blockade as they confront a protester along Baum Boulevard.
Police watch as protesters run off from Baum Boulevard during a march by demonstrators on Thursday.
Police form a blockade as they head to confront protesters along Baum Boulevard.
A large group of police stand across Baum Boulevard after a protest march turned violent on Thursday. Protesters threw rocks at police and broke several windows along their march from Lawrenceville.

These are a few of my images from my coverage of the G20 Summit in Pittsburgh on Thursday, September 24, 2009.