BOSTON (CBS) – A Beacon Hill woman who struck and killed a 5-year-old girl and her 2-month-old baby sister in Revere has been sentenced to 4.5 years in prison. Autumn Harris, 43, pleaded guilty to motor vehicle homicide charges during a change of plea hearing on Zoom Tuesday.

In December 2018, Harris was driving an SUV on Revere Beach Parkway when she struck a group of people who were standing on the center median waiting to cross the street.

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Five-year-old Adrianna Mejia-Rivera was pronounced dead at the scene. Her baby sister, Natasha Nicole Mejia-Rivera, died several days later.

Adrianna Mejia-Rivera and Natasha Nicole Mejia-Rivera. (Family Photo)

Harris failed a series of sobriety tests after the crash but a blood test yielded a negative result for alcohol. She said she had taken a muscle relaxant and melatonin the previous night, only slept for two hours before working for a full day, and admitted she may have “nodded off” while driving.

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Autumn Harris appears at a pretrial hearing on January 10, 2019. (WBZ-TV)

“Two beautiful children are gone as a result reckless behavior that could have been prevented,” Suffolk County District Attorney Rachael Rollins said. “Ms. Harris may not have intended to cause harm, but she failed to show any concern for the foreseeable consequences of driving a nearly two-ton vehicle while incapacitated.”

Rollins said there would have been a different outcome if the case of intoxication had been stronger.

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A Suffolk Superior Court judge sentenced Harris to a total term of 4.5 years in prison, six months suspended and four years of probation following her release. She will lose her license to drive for 15 years and will be subjected to random alcohol and drug testing.