LOS ANGELES—A passenger aboard a Delta flight from Los Angeles International Airport (LAX) to Seattle was detained Saturday for allegedly opening an emergency exit door aboard the plane and causing the emergency slide to be activated.

The action happened at approximately 10 a.m. Saturday, as the airplane pushed away from the gate. Los Angeles Airport Police detained the passenger for further investigation, according to Los Angeles Police Capt. Karla Rodriguez.

“Due to the circumstances, FBI has been notified,” Rodriguez said. “The aircraft was returned to a gate and passengers are in the process of being deplaned in order to be transported in another aircraft so that they can continue with their flight plans.”

She added that no arrests were made but the “subject was transported to a local hospital for a mental evaluation.”