The popstar feared the fan might have a gun as she was quickly taken off stage amid booing from the packed crowd at Planet Hollywood on Wesneday night.
Video of the incident was uploaded to Instagram and shows the 35-year-old performing hit song (You Drive Me) Crazy.
As she finishes the song there is suddenly a commotion as a fan can be seen trying to get onto the stage behind the singer.
Britney Spears feafred the fan might have a gun as he invaded the stage in Las Vegas
Within seconds he is surrounded by security guards as two burly bodyguards appear from nowhere and flank the Oops I Did It Again star.
She can be heard saying: “What’s going on? Is everything ok?
Her voice then audibly becomes more fearful as she asks: “He’s got a gun?”
Britney was performing one of her hits at Planet Hollywood when the fan rushed the stage
As the security men deal with the crazed fan, the town bodyguards decide not to take any risks and escort the star off stage.
Boos ring out around the arena as she departs under the protection of the pair.
Britney’s Piece Of Me Vegas residency in the Nevada city, which has earned over $100 million in ticket sales, will come to a close this December after first debuting in 2013.