Lies of San Francisco Mercedes driver, 79, are exposed after she killed couple and their infants with her SUV

A San Francisco Mercedes driver charged with killing a couple and their two children changed her story about caused the fatal crash.

Mary Fong Lau, 79, is accused of mowing down Diego Cardoso de Oliveira, 40, Matilde Ramos Pinto, 38, and their two children with her SUV as they waited at a bus stop in the West Portal neighborhood. 

The San Francisco Standard reported that Lau told witnesses at the scene that she was trying to park when she accidentally hit the accelerator during the fateful incident on March 16.

However, Lau told cops at the hospital that the 2014 Mercedes-Benz GLK 350 she was driving malfunctioned before she plowed into the bus shelter where the family of four was struck.

Investigators found no problems with Laus car, which they said was traveling at an estimated 66 to 75 mph, the Standard reported.

The crash killed the couple and their sons, 1-year-old Joaquin Ramos Pinto de Oliveira and three-month-old Cauê Ramos Pinto de Oliveira, as the family was waiting to catch a bus to the zoo.

The Mercedes driver charged with killing Diego Cardoso de Oliveira, 40, Matilde Ramos Pinto, 38, and their two children changed her story about what caused the crash

Lau has pleaded not guilty to vehicular manslaughter. She was ordered not to drive and to turn over her drivers license to the court, where she will appear again on January 22.

Her attorney, Samuel Geller, told the Standard that there is a level of hearsay in the witness statement given to police, noting that the witness was paraphrasing comments made by Lau in the wake of a traumatic incident.

I would ask the public to reserve judgment until the court process has taken its course, Geller said.

This is a horrific tragedy, and Ms. Lau continues to mourn this incident to this day. 

Some witnesses said Lau suffered a medical incident before the crash. Others said she got out of the car yelling, What have I done? 

Diego and Joaquin were killed at the scene while Matilde and Cauê succumbed to injuries in hospital.

Lau has pleaded not guilty to vehicular manslaughter. She was ordered not to drive and to turn over her drivers license to the court

The family lived in the Mission District and planned to spend a day at the zoo for their wedding anniversary 

The family lived in the Mission District and planned to spend a day at the zoo for their wedding anniversary, friends said.

Diego, a creative director at Apple, was from Brazil and Matilde was a film and advertising producer from Portugal.

Other people waiting for the bus to arrive were also injured in the crash and received medical attention. 

One witness, Nikki Mashburn, told The San Francisco Chronicle that she heard the crash and that is sounded like an explosion. She said that the victims suffered head injuries.

When the paramedics showed up, you could tell … they didnt know what to do first, Mashburn said.

Joaquin Ramos Pinto de Oliveira, 1, was killed at the scene along with his father, while his brother and mom died at the hospital

Following the tragedy, advocacy group Walk San Francisco and locals voiced concerns about the intersection of Ulloa Street and West Portal Avenue where the bus stop is located 

Following the tragedy, advocacy group Walk San Francisco and locals voiced concerns about the intersection of Ulloa Street and West Portal Avenue where the bus stop is located.

The group noted that around the intersection, there are multiple places frequented by families and children, like a library, schools and train stations.