A spontaneous musical concert at a California shopping mall ended with the entire complex being evacuated after some 5,000 people turned up to sing.
The incident happened at the Roseville Galleria shopping mall, which is reported to have started shaking due to the volume of people inside.
Fire and safety officials struggled not to spoil the festive mood as they evacuated the mall.
One warden said: "You can keep singing, but please walk".
The music? Handel's 'Hallelujah Chorus' from The Messiah. :)