A 9-year-old Minneapolis boy hopped on board a Delta flight Thursday without a ticket and flew to Las Vegas, where police caught up with him and took him into protective custody.

How the boy was able to get through security checkpoints, into gate areas and finally onto the plane was unclear.

A Delta spokeswoman said Saturday night that the airline is investigating the incident, which also was reported to the U.S. Transportation Security Administration, Minneapolis police and the Hennepin County attorney’s office.

According to Patrick Hogan, a spokesman for the Metropolitan Airports Commission, the boy was screened by security agents at Minneapolis-St. Paul International Airport shortly after 10:30 a.m. Thursday and went to Concourse G, where he boarded a Delta flight leaving for Las Vegas at 11:15 a.m.

Hogan said the flight crew became suspicious of the boy while in flight and contacted Las Vegas police, who met the flight when it landed and transferred the boy to child protection services.

KARE-TV reported Saturday night that the boy was returning to the Twin Cities and that his parents were working with Las Vegas and Hennepin County authorities.