The Sun, citing charging documents, reports officers told Johnson her car would be towed and she would have to appear in court.
Johnson allegedly told the officer, "It don’t matter, I won’t be here in five days."
She also allegedly said, "Y'all going to see me on the news making my big debut."
Officers reportedly noticed the smell of decomposition, then discovered the bodies when they were clearing her trunk to prepare it for towing, The Baltimore Sun reports.
According to the Sun, one body was in a suitcase and another in a plastic bag.
Johnson allegedly tried fleeing the scene on foot.
Baltimore County Police identified the victims, who were siblings and Johnson's niece and nephew, as 7-year-old Joshlyn Johnson and 5-year-old Larry O'Neil. Joshlyn and Larry had reportedly been in her care since 2019.
Joshlyn's body was in the suitcase, and police said she died after Johnson allegedly hit her several times, causing Joshlyn to fall and hit her head.
Larry died about two months ago, the Sun reports. Johnson said the boy told her he was tired, then laid down and never woke up, according to charging documents. His body was found in a tote bag in the trunk next to his deceased sister.
Autopsies determined the 7-year-old girl weighed 18 pounds when she died, and the 5-year-old weighed 21 pounds, WBFF-TV reports.
Police said the children's biological mother was unable to provide for the children and left them with her sister, WBFF reports.
The Office of the Chief Medical Examiner is working to determine causes of death.
Baltimore County Court records show Johnson was booked on 10 charges, including four counts of first-degree child abuse and two counts of burying/disposing a body in an unauthorized place. She was held without bond.