Doctors struggled on Wednesday to save the life of an Iraq war veteran who became a rallying cry for the Occupy Wall Street movement after he was badly wounded in clashes between protesters and police.
Scott Olsen, 24, a former US Marine who served two tours of duty in Iraq, was struck in the head by a tear gas canister fired on Tuesday by police trying to prevent protesters from reclaiming a public square, protest organisers said.
Police had forcibly cleared Frank Ogawa Plaza, which had served as a base for two weeks of protests in Oakland against economic inequality, in a predawn sweep of the area earlier that same day, arresting 85 protesters at a makeshift encampment there.
A spokesman for Highland General Hospital in Oakland confirmed Olsen was listed in critical condition from injuries sustained in the protest but could not say how he was hurt.
Oakland police have acknowledged officers fired tear gas and so-called "bean-bag" projectiles to disperse demonstrators on Tuesday night but declined to discuss how Olsen may have been hurt.
News of Olsen's injury ignited a furor among supporters of the protests.