After asking fans if they were having fun, the "Toxic" singer, 35, quickly became aware of the chaos behind her.
The man was identified as 37-year-old Jesse Webb.
Webb allegedly rushed the stage after being asked by security to leave the show because he had been acting disorderly, TMZ reported. She asked, anxiously, sheltering behind the wide body of one of her bodyguards.
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After security gets hold of the man, a fan video shows Britney being escorted offstage for safety.
It is still unknown if he was armed, but security was able to safely get the man off the stage. And in the middle of the show a random man climbed up on stage. On the way out, he can be seen struggling with security and attempting to kick one of the guards. The singer came back to finish the show shortly after, and the rest of the night reportedly continued smoothly.
The Las Vegas Metropolitan Police Department and Planet Hollywood's parent company, Caesar's, did not immediately respond to USA TODAY's query about whether the man's identity and whether he was arrested. "I'm sooooo excited to see you all!" she wrote on Instagram prior to the concert.