CHICAGO (NewsNation) — A man is in custody after opening a plane’s emergency exit and walking onto the wing of a moving aircraft at Chicago’s O’Hare International Airport.

The incident happened around 4:30 a.m. Thursday while a United Airlines plane was approaching the airport’s gate.

Police said a man onboard the plane pulled the emergency exit door and walked out onto the wing of the plane, then slid down onto the airfield. He was stopped by ground crew members before being apprehended.

The airline said in a statement to NewsNation “The plane then arrived at the gate and all passengers deplaned safely.”

“The safety of our customers and crew is our highest priority,” United Airlines added.

Charges are pending. It is unclear at this time why the individual exited the plane in this manner.