A tourist visiting the Demilitarized Zone (DMZ) who saw a U.S. soldier bolt to North Korea says she thought at first it was a “really stupid prank.”

Sarah Leslie and her father, visiting from New Zealand, were part of a group that left Tuesday morning from Seoul to visit the DMZ and tour the border village of Panmunjom. She told The Associated Press that Pvt. 2nd Class Travis King was part of the 43-member group, but he was dressed casually in jeans and a T-shirt, so she did not know he was a soldier.

She said as the tour was coming to an end, she saw King running “really fast,” darting about 30 feet in between buildings before crossing and disappearing behind the border.

“I assumed initially he had a mate filming him in some kind of really stupid prank or stunt, like a TikTok, the most stupid thing you could do,” Leslie said. “But then I heard one of the soldiers shout, ‘Get that guy.’”

She said the soldier who shouted to stop King was a U.S. soldier patrolling the area, but the soldiers did not have enough time to respond. She said she did not see anyone on the North Korean side of the border.

The American-led United Nations Command announced Tuesday that a U.S. national crossed the border during the tour of Panmunjom and was being detained by North Korea. U.S. officials later identified King as an Army soldier, saying he “willfully” crossed the border.

Officials say King was recently released from a South Korean, prison, where he was being held on assault charges. He was slated to return to Fort Bliss, Texas, on Monday, but he joined the tour group instead of boarding his plane.

Leslie noted the tour visited the Joint Security Area in Panmunjom, where they could step on North Korean soil from inside one of the jointly held buildings. She added she needed to give her passport and get a permit in advance of the tour.

She also said the soldiers took the tourist group to give statements about what happened after the incident.

“People couldn’t really quite believe what had happened,” Leslie said. “Quite a few were really shocked. Once we got on the bus and got out of there, we were all kind of staring at each other.”

The Associated Press contributed.