As 4-month-old Morana Cost-Corbitt fights for her life, her family is pleading for the public’s help.

"Please call the authorities,” the girl’s aunt, Adrianne Caddle, told Channel 2 Action News. “Tell them everything you know so that we can put closure to this.”

Morana’s mother, Lanicia Cost, was driving the family of five home about 6 p.m. Sunday when their lives were turned upside down.

RELATED: 2-year-old killed, baby critically hurt in crash

A blue sedan with a New York tag cut off the family’s 2011 Ford Explorer on I-75 North near Charles W. Grant Parkway, Clayton County police Sgt. Ashanti Marbury said.

To avoid a collision, Cost swerved and the SUV flipped. The blue sedan continued on I-75 North, police said.

"I think that's heartless,” Caddle said. “That's very heartless."

Two-year-old Michaela Cost died at the scene. Morana, her sister, was taken to Children’s Healthcare of Atlanta at Egleston in critical condition. Another sister, 4-year-old Micole Cost, was treated for minor injuries and released.

A 2-year-old girl was killed and a 4-month-old is in critical condition after their family's SUV crashed on I-75 North. The victims' parents and  4-year-old sister sustained minor injuries.  (Credit: Channel 2 Action News)
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The victims’ parents, Cost and Michael Corbitt, were taken to a local hospital with minor injuries. They were too distraught to speak.

“She doesn’t talk much,” Caddle told Channel 2. “Michael is just as bad.”

Authorities are looking for the sedan, which should have front-end damage.

The Georgia State Patrol is investigating the accident.

Anyone with information on the crash is asked to call Crime Stoppers at 404-577-8477.