Fans of San Diego State's baseball team expected to see players donning costumes at the program's annual Halloween Game on Sunday afternoon.

But the crowd did not expect to see a surprise flash mob take place on the field!

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The video starts with confused onlookers noticing one of the costumed players fall down on the pitcher's mound. Then — as a cloud of fog covers the field and Michael Jackson's 'Thriller' takes over the stadium's speakers — they jump right into a group choreographed dance to the classically spooky tune!

Watch the video below to see the awesome, Halloween-inspired flash mob.