When Tara Dragon Hernandez's baby was diagnosed with neuroblastoma cancer she took a leave of absence from her job as Vice Principal at Woodlake Elementary School in Louisiana.

She was out for the school year, but returned to school on Monday for what she thought was the annual end-of-year assembly, WWLTV reports. Students and faculty surprised her in a big way though. Approximately 800 children and teachers formed a flash mob; they sang and danced to Bruno Mars' "Count On Me" in honor of Hernandez, her baby Grayson (who is now 10 months old) and the rest of their family.

The show brought Hernandez to tears.

"You know people are there for you but then to see that, when push comes to shove, it was beautiful," she told the news station.

Baby Grayson has already been through four rounds of chemotherapy, but his mom said there is still "two percent of active cancer tumor cells left in his body." At this point, "it's just kind of a wait and see," she said.

One student, 6-year-old Evan Cooper told WWLTV that the flash mob was "for baby Grayson to help him get better."

Watch the video above to see the flash mob in action, interviews with the kids and click over to WWLTV for more of Grayson's story.

h/t The Stir