Authorities are searching for a healthcare reform activist today who they said bit off the finger of a 65-year-old counter-demonstrator during a fight at a MoveOn.org rally in Thousand Oaks.

"It all started with their difference in philosophy over healthcare reform," said Senior Deputy Eric Buschow of the Ventura County Sheriff's Department.

The incident occurred about 7 p.m. Wednesday at a "We Can?t Afford to Wait Vigil" organized by affiliates of the activist group MoveOn.org, which drew supporters of President Obama?s healthcare plan, Buschow said. The rally also attracted several counter-protesters, he said.

During the rally at Lynn Road and Hillcrest Drive, near the Oaks Mall, the two men got into a heated argument and began fighting.

"At which point, one man bit off the left pinky of the other," Buschow said.

The injured demonstrator then drove himself to Los Robles Hospital and Medical Center about a mile away, he said.