A San Francisco cable car slammed on its brakes to avoid hitting a car, and 12 passengers sustained minor injuries. Six of them were treated at Mission Emergency Hospital, while the others declined hospital care. The emergency brake, a metal wedge that drops into the cable slot, caused the cable car to stop abruptly, Municipal Railway spokeswoman Anne Milner said. Gripman Tom O'Brien pulled the brake to avoid hitting a car pulling out of a garage, she said. Shuttle buses were used until cable car service was restored.