The singer Patti LaBelle was rushed off stage two songs into her Christmas concert in Milwaukee in the US after a bomb threat forced authorities to evacuate the theatre.

Video from the Riverside Theatre on Saturday night shows what appears to be two security officers interrupting the 78-year-old LaBelle as she chats with an audience member.

They rush her off stage. Shortly after, someone announced that the nearly full 2,500-seat venue had to be evacuated because of a bomb threat.

Catherine Brunson, who documented the evacuation on Facebook Live, told the newspaper that the evacuation happened two songs into LaBelle’s concert around 9.24pm.

“We came out and police had the block taped off… A whole lot of people were pretty upset… It’s scary,” Brunson said.

Scott Pierce, who also attended the concert, said everyone left the theatre calmly, but it’s “just sad that someone does this”.

Milwaukee Police Captain Warren Allen Jr said in a statement the theatre was searched and no explosive devices were discovered, so there was no threat to the public.

The operator of the Riverside Theatre, Pabst Theatre Group, said it would work with LaBelle to reschedule the show.