Scott Thomas Olsen, a 24-year-old former Marine who served tours in Iraq in 2006 and 2007, is in critical condition after being seriously injured by one of the projectile gas canisters fired at Occupy Oakland protesters last night.

Captured chillingly in the video above, the canister hit Olsen's head above his right eye. When he failed to respond to basic questions, he was rushed to hospital where doctors found him to have a skull fracture and brain swelling. He's at serious risk of permanent brain damage.

Olsen works as an IT systems analyst in San Francisco, and had spent several nights camping out with Occupy San Francisco before moving on to the Oakland encampment. His two tours of duty deployed him to the Iraqi-Syrian border city of Al Qaim and to Haditha, both "hotbeds of al-Qaida and insurgent activity." His Facebook page lists #OccupySF and Veterans For Peace among his "likes."

Olsen's injuries are the most severe yet to come out of the protest clashes. Our thoughts are with him for a speedy recovery.

UPDATE: A second video making the rounds shows an officer launching a flash grenade directly into the middle of a group of protesters coming to Olsen's aid.

[, Photo via Facebook]