United Kingdom, June 26 -- Lorde was threatened with arrest by anti-terrorism police.

The 28-year-old singer had planned to film the music video for What Was That? in Washington Square Park in New York, but after posting about it on her Instagram Story, "such a mob showed up that the cops shut it down", and Lorde received a stern warning from officers.

Speaking on The Late Show with Stephen Colbert, she said: "We had the anti-terrorism unit being very intense, telling me if I stepped on the premises I would be arrested for riot incitement."

The Royals hitmaker "couldn't show up for many hours" but eventually returned to the park to shoot the video on a tight timeline.

She explained: "I came back later, they said, 'You can go out, you ...