The girl, who remains unnamed, left home for school on April 26, according to the Associated Press.
But she didn’t return home.
Alexander Rzhanenkov of the St. Petersburg city hall told Russian news agencies on April 27, the girl went to Moscow’s Vnukovo airport where she mingled with a crowd boarding a flight to St. Petersburg.
She then got on board with a large family with children.
Police picked her up at St. Petersburg’s airport, where she was found alone.
It was reported that the girl had never been on an airplane in her life—until Tuesday.
The incident was called a “serious alert sign” regarding airport security by children’s rights ombudsman Pavel Astakhov on Wednesday.
According to RT News, The Rossiya airline and the Moscow airport will face an investigation due to Tuesday’s incident.
The mother of the child also plans to sue both the Moscow airport and the carrier for compensation, and for failing to carry out proper checks, RT News reported.
The Associated Press contributed to this report.