UPDATE 3:21 P.M. EST: Kanye West was spilling all sorts of tea about Jay Z.
He could be heard yelling mid-concert:
Yikes! You can watch the tense moment for yourself (below):
Along with Jon Bon Jovi, Earth, Wind & Fire, Stevie Wonder and Jennifer Hudson, Katy sang her heart out at the Nokia Theatre with hopes of re-electing the Democratic nominee.
She belted out one of her biggest hits, Firework (above) and then covered Al Green's Let's Stay Together to show the POTUS how it's done!