The Irish rock band was forced to postpone a concert in Stockholm last night following a security threat.

U2 were due to play the Globe Arena but shortly before the show began the venue was evacuated.

According to unofficial reports, a gunman entered the arena after claiming to be an off-duty police officer. While helicopters circled outside, security cleared the building and carried out a full sweep to find the man.

#U2ieTour #U2Stockholm Seated fans are outside, GA fans in seats. Police searching inside for someone or something.Situation not fully clear — U2tour (@U2tour) September 20, 2015

Official reports, however, currently refer only to “a security breach”. A statement posted on U2’s website on Sunday says, “As the breach has not been resolved quickly and as audience safety is paramount, the police have advised The Globen and Live Nation that they have no option but to postpone tonight's show, to a rescheduled date of Tuesday 22nd September... The organisers apologize for the inconvenience caused and thank the audience for their understanding. Their safety is the priority.”

Part of the crowd singing One. Security guy to us: “We are in this together…as One.” #U2ieTour #U2Stockholm — Lukas Biba (@bibalukas) September 20, 2015

Why is the new U2 album in your iTunes library?

According to the Swedish website Expressen, a police spokesman said that there are no suspects and no one has been arrested but that they were called to investigate a violation of the Arms Act.

The site claims that initially the organisers told fans that the ticket scan system had failed, despite already letting them into the venue. A man had reportedly entered with a weapon concealed in a bumbag. The police then searched everyone who left the venue during the evacuation.

U2 are currently in the midst of a sold-out world arena tour and are due to play six nights at London’s O2 Arena in October and November.