A Delta Air Lines co-pilot was taken into custody shortly after landing at San Francisco International Airport Saturday, according to passengers who witnessed the incident.

The co-pilot was handcuffed and pulled off the flight by the agents, some of whom were identified as Homeland Security investigators.

A Delta Air Lines co-pilot was taken into custody by federal agents shortly after landing at San Francisco International Airport on July 26, with unconfirmed reports that the arrest was in connection ...