(CNN) -- When a New York elementary school invited rock star Billy Joel to a tribute concert of his greatest hits, the last thing they expected was for him to actually show up.
But that's exactly what the "Piano Man" singer did.
Vocalists in grades kindergarten through second performed "The River of Dreams: A Billy Joel Tribute Concert" on Wednesday in front of an audience consisting of their peers, teachers, families -- and Billy Joel himself.
"We really didn't expect him to come," Nomi Rosen, principal of Deasy Elementary School in Glen Cove, Long Island, told CNN Thursday.
Joel, who is a Long Island local, found out about the concert after word of mouth spread through the area, Rosen said.
Joel arrived just five minutes before the concert began and took a seat in the back. "I ran up to him to see if he wanted to go up to the front, and he said 'No, no, I don't want the kids to be nervous,' " Rosen recounted.
With his permission, Rosen announced on stage that the "Uptown Girl" singer was present "and that's when the roars started."
Joel hits that were featured were "Movin' Out," "We Didn't Start the Fire," and "Uptown Girl." The tribute closed out the festivities with "New York State of Mind" and "Piano Man," according to a statement on the school district's website.
Every spring at Deasy Elementary, the music teacher prepares a tribute to a different artist. Last year, it was the Beatles, although this is the first time the artist being honored actually showed up, Rosen said.
According to Rosen, the parents and the older students were in awe at the singer's presence, but not everyone was as impressed. "The younger kids were like, 'Of course he is coming. We're singing his songs he wants to hear us sing!' "
Joel is on tour and not available for comment, according to representatives for the singer.