Holiday shoppers at RiverTown Crossings mall in Grandville received a big surprise when a flash mob sang "Amazing Grace" on Saturday.

A large crowd filled with participants and onlookers gathered in the mall. It wasn't long before some of those onlookers became participants too.

Here's a couple of looks at the flash mob's performance. The faces of those surprised by the performance provide the biggest highlights, that and the bagpipes.