Caught in the Act

Justin Bieber & Selena Gomez Sneak Smooches at Charity Event

04/18/2012 at 05:45 AM EDT

Young love in South Florida!

Selena Gomez joined boyfriend Justin Bieber at a jam-packed event for his Pencils of Promise Charity at St. Andrews School in Boca Raton. The charitable organization builds schools for the underprivileged around the world, and Bieber stopped by to congratulate several students on their great fundraising efforts.

"When Justin wasn’t interacting with the group, he and Selena were behind [the] stage and in the backyard area making out," an eyewitness source tells PEOPLE. "It was amazing to see a young couple so much in love."

While in town, the two also the couple stopped by the oceanfront Breakers hotel in Palm Beach – then headed over to nearby Jupiter, Fla., for a private event.
– Linda Marx

NEXT: New Parents Hilary Duff & Mike Comrie Step Out for Grown-Up Dinner Date