Alarms sounded throughout the zoo, a tourist card that was closed to the public at the time, before the lions were located and returned to their exhibit. Zoo executive director Simon Duffy told reporters a lion needed to be tranquilized. “This is a major incident and a full review is now underway to confirm exactly how the lions were able to get out of their main exhibit,” he said. “We don’t have the exact details of how and why this happened.”