HONG KONG — Dua Lipa, a 23-year-old British pop star, was crooning and grooving on stage. The crowd cheered, some waving signs with the singer’s name glowing pink.

But what started as a jubilant night out for young music fans in Shanghai descended into violence when security workers pulled people from their seats.

Video footage circulated of security guards shoving and dragging concertgoers from the venue. Music fans across China expressed outrage, describing the removal as unwarranted.

Yixuan Zhang, 27, had been so excited about the concert that he ordered a telescope online to help him see the stage more clearly.