A nine-year-old boy was able to sneak onto a plane undetected to Las Vegas Wednesday morning.

According to Good Morning America, the boy, whose name has not been released, boarded a Delta flight going from Minneapolis to Las Vegas. While during the flight, the crew felt suspicious towards the boy. They contacted the Las Vegas police and they arrived when the plane landed to pick up the boy.

“The fact that the child’s actions weren’t detected until he was in flight is concerning,” said Metropolitan Airports Commission spokesman Patrick Hogan. “More than 33 million people travel through Minneapolis-St. Paul International Airport every year, and I don’t know of another instance in my 13 years at the airport in which anything similar has happened.”

The Associated Press reports that while at the airport the boy ate lunch, but left without his bag or paying the bill to go to the bathroom.

The boy was taken into child protective services. Delta airlines have opened an investigation on how the boy was able to pass through security and board the plane without a boarding pass.