OAKLAND — A 25-year-old man was charged with attempted murder of a San Francisco police officer after striking him with a car during a hectic incident where an Oakland officer fired his gun into the ground, according to court records. Joseph Willis was charged with attempted murder, three counts of assault upon a police officer with a deadly weapon, attempted carjacking and illegally possessing a gun and ammunition. The attempted murder charge, which carries a potential life sentence, requires prosecutors to prove he intended to kill the officer. San Francisco police chased Willis, the alleged driver, and another man into Oakland during an attempted traffic stop on Tuesday, authorities said. Prosecutors allege Willis attempted to carjack a motorist to get away from police.