It has not been a good few months for the Roseville Galleria mall near Sacramento. First, a guy barricaded himself inside a GameStop and started a fire that damaged a big portion of the mall about a month ago. And now, Monday night, they had a flash mob.

A flash mob? Big deal, right? A few hundred people show up in the food court to sing the Hallelujah Chorus? Pretty benign, right? Well, so many people showed up that the mall was evacuated and shut down due to safety concerns. People in the crowd said they heard the building pop and creak and felt the floor shift.

Now, THAT’S a flash mob.

Coverage from the ABC affiliate, KXTV: