A former UC Berkeley student and tree-sitter who was critically injured Friday while protesting the construction of a wall in the West Bank village of Na'alin is still in critical condition.

Oakland resident Tristan Anderson, 38, was hit in the head with a tear gas canister fired by Israeli soldiers and remains unconscious at a hospital in Tel Aviv, said Sasha Solanas, a volunteer for the International Solidarity Movement. The movement is a Palestinian-led human rights organization dedicated to resisting Israeli military forces.

Anderson was injured during a protest against a wall that Palestinian villagers from Na'alin say prevents them from accessing farmland, according to his friend Kate Raphael.

"It was a large demonstration, and (Anderson was) far from anyone who was stone-throwing," Raphael said. "He really was at the wrong place at the wrong time."

Solanas said the protest had ended and that Anderson was in the sidelines when the canister hit his head, damaging his frontal lobe, from 60 meters away.

"He had a gaping hole in his head," Solanas said. "He had surgery in his brain and in his eye."

A spokesperson for the Israel Defense Forces said the protest took place in a military zone that is off-limits to demonstrations and that Israeli troops were reacting to rock-throwing from demonstrators, according to Haaretz Service, an Israeli daily newspaper.

But Raphael said doctors suggested that the severity of the injury was related to the way the canister was fired.

"I was told that from the injuries, the doctors said it was not fired at an arc, which was the army's regulation," Raphael said.

Paul Larudee, co-founder of the movement's Northern California chapter, said volunteers have been caught in cross-fire before.

"Several of us have been harmed, with many wounded, but nothing serious except for a few cases," he said.

According to Raphael, Anderson had been in Israel for a month traveling with his girlfriend. He then became involved in both the movement and Anarchists Against the Wall, an organization of Israelis supporting Palestinian efforts to resist the wall.

Up until last September, Anderson was involved in a nearly two-year-long tree-sit at UC Berkeley protesting the construction of an athletic center near Memorial Stadium.

Matthew Taylor, a Bay Area activist and author who knew Anderson during the tree-sit, said Anderson was active in creating social change.

"He protested against the Iraq War, free trade agreement to exploit the global South, and is now protesting against the theft of Palestinian land," he said. "He is a very caring dedicated man who has put his life on the line for social and environmental justice."

Anderson's friends have organized a 4 p.m. protest today at the Consulate General of Israel in San Francisco to support Anderson and his cause.

Tags: WEST BANK, MEMORIAL STADIUM, TREE SIT, OAK GROVE