Gina Eunice hit 56-year-old Chinese citizen Yuee Yao, her son Kai Yuan and two friends around 9 p.m. on Dec. 20, 2012, on Christmas Tree Point Road, District Attorney George Gascon said.
The group was looking at the city views before the holidays when Eunice, who was speeding and driving under the influence, slammed into them. Yao was knocked down a hillside and killed, according to prosecutors.
Eunice fled the scene but was later found at a nearby parking lot. She allegedly had a blood-alcohol content of .23 at the time of the collision, prosecutors said.
Eunice was arrested and charged with felony vehicular manslaughter, felony DUI causing injury and hit-and-run.
She pleaded guilty Wednesday to the charge of vehicular manslaughter while intoxicated and received the four-year sentence and a strike under the state's "Three Strikes" law.
She faced the potential of 10 years in prison before a plea bargain was reached this week, Gascon said.
"This is tragic all the way around," he said. "So many lives are ruined."
He said Yao's family is satisfied by what he called the "very severe" sentence, but said it "still does not bring a life back."
The announcement of Eunice's sentence comes after two fatal pedestrian incidents occurred in San Francisco in the past 24 hours.
An elderly woman was fatally struck by a car in Chinatown on Thursday morning and this morning a Recology truck fatally struck a pedestrian in the Tenderloin.
Gascon emphasized the importance of traffic safety for pedestrians and drivers and noted that reducing speeds, avoiding distracted driving and never drinking and driving can make streets safer.
"Hopefully we can end the year without additional fatalities," he said.
Nicole Schneider, executive director of Walk San Francisco, a pedestrian advocacy group, said there have been more pedestrian fatalities this year compared to last.
"It's no lie that our streets are not safe for pedestrians," Schneider said.
She called for the city to fix its most dangerous streets, in part, by making pedestrian-friendly designs and increasing enforcement by the Police Department.
There have been 17 pedestrian fatalities so far this year, Schneider said.
"We hope that next year we don't see this number of fatalities," she said.