One person was killed when a car plunged off the San Francisco-Oakland Bay Bridge and landed in shallow water near the shore of Yerba Buena Island after bouncing down the steep cliff. The victim was not immediately identified. The California Highway Patrol said the westbound car apparently struck a bridge support cable on the upper deck, flipped into the air and plummeted from the bridge down the side of Yerba Buena Island, halfway between San Francisco and Oakland. Coast Guard patrol boats searched the area for bodies of other possible victims but found none. The mishap was the second major accident on the span in two days. Both occurred under eerily similar circumstances. Four people were seriously injured Saturday when the taxi they were passengers in apparently lost control on the lower deck and hit a bridge support.