K-pop boy band VIXX had the rare opportunity to meet a couple of international superstars recently.

In pictures released through social media, the Korean pop stars were seen brushing elbows with the likes of R&B singer Usher and Black Eyed Peas member will.i.am at a recent event celebrating Earth Day.

The boy band traveled to Washington DC this past weekend to attend the Global Citizen 2015 Earth Day as special guests and representatives of South Korea.  Solo singer Roy Kim also joined them.

The free live music event, which was held on Saturday, April 18 on the grounds of the Washington Monument, brought together musicians and other notable celebrities from around the world. Performers included Usher, No Doubt, Fallout Boy, and Mary J. Blige and was hosted by will.i.am.

VIXX members Hyuk and Hongbin shared a picture they snapped with Usher. "Usher, who showed us a passionate stage in the fighting spirit despite hurting his leg! I...love...no..respect you," wrote Hyuk on his official Twitter. The group also gave the American singer a signed copy of their Error EP.

Additionally, VIXX member Leo took a selfie with regular K-pop collaborator will.i.am and uploaded it on VIXX's official Twitter page.