U2 cancelled its concert at the Globe Arena in Stockholm, Sweden on Sunday following reports that a gunman had entered the arena disguised as an off-duty police officer, according to The Telegraph.
The venue was evacuated just before the show was scheduled to start as air and ground units conducted a full sweep of the building and nearby areas to search for the man.
Stockholm police spokesman Kjell Nildgren said that Sunday's show was cancelled because organizers reported a breach at the security check and ticket control points as concertgoers were entering the venue.
"They decided to stop the entrance for spectators and get the people out that had come inside in order to search the area, " Nildgren said Monday, adding that the event organizers believed the security checks had not been carried out properly, according to The New York Times.
"We are investigating a crime against Swedish weapon laws," Nildgren said, adding that police had not yet found any suspicious "persons or objects."