The Uptown Funk singer was performing at Glasgow Green on Tuesday when concertgoers say pyrotechnics started a fire, causing the star to take a break.
One fan tweeted a picture of a safety message that flashed up on one of the giant screens in the outdoor venue.
It read: “This is a safety announcement. It is necessary to stop the show temporarily. Further information to follow.”
Along with the image, the fan wrote: “Bruno Mars is on FIRE (no, seriously... they’ve had to temporarily stop the show because of the fireworks ...) thanks to the team for extinguishing.”
Concertgoers say the singer returned to the stage around seven minutes later, adding that Mars made a joke about the safety scare.
The fan tweeted: “Lols @ BrunoMars singing ‘We burned the stage down in Glasgooooow’ after pyrotechnic misfired and hit overhead lights.”
Mars, 32, is set to perform in London later this week where he is due to play Barclaycard’s British Summer Time Festival on July 14.
He is currently on his 24K Magic World Tour.
Mars’s representatives have been approached for comment.