Bono U2 singer
Bono, frontman for U2, defended the idea Syrians fleeing their homeland are refugees, not "migrants" during a visit to the Expo 2015 global fair in Milan. Reuters/Alessandro Garofalo

A U2 concert in Stockholm was evacuated Sunday night because of an unresolved security threat. Fans were forced to leave the Globe Arena in the Swedish capital around 8 p.m., local time, and the concert was rescheduled for Tuesday.

What exactly forced the evacuation wasn't immediately clear though a number of fans posted images of police sweeping through the arena during the evacuation. Security teams appeared to be looking around on the floor, where fans who purchased general admission seats stood not long before, and a heavy police presence was on display outside the building.

A bomb threat was made against the venue, the New Musical Express reported, with police said to be checking beneath arena seats., a Sweish news outlet, indicated earlier an armed man disguised as a police officer was arrested on the scene.

U2 is scheduled to play the Globe Arena as part of the Irish band's “Innocence and Experience” tour.

Earlier this month U2 frontman Bono blasted the use of the word “migrant” to describe the Syrian refugees fleeing a war-torn country to seek asylum in Europe and the United States. The debate over whether or not to accept the refugees has galvanized much of Europe, particularly in Sweden and Finland where refugees have run into repeated roadblocks from angry citizens.

“ 'Migrant' is a political word, used to take away the real status of these people -- they are refugees,” Bono said during a panel on world hunger, adding, so many people are not leaving their homeland because “they want to live in Italy or Ireland.”