Hillary Clinton made a surprise appearance at tonight’s UNICEF Snowflake Ball in New York to introduce Katy Perry, the singer and UNICEF Goodwill Ambassador honored with the organization’s Audrey Hepburn Humanitarian Award.

“We need champions like Katy, now more than ever,” Clinton said. Her appearance was among her first since losing the presidential election to Donald Trump, and was greeted with a standing ovation.

Audience members tweeted that Perry was surprised by Clinton’s arrival on stage, and was moved to tears.

“Truly my work has just begun, and this award is a starting line, not a finish line,” Perry said in a part of her acceptance speech that was later tweeted by UNICEF.

Thanking Clinton, Perry said, “Hillary has lit that voice inside of me, and that light will never go out. It will continue to get brighter and brighter and brighter.”

The UNICEF gala, held Manhattan’s Cipriani Wall Street, was hosted by Octavia Spencer, with performances by the cast of The Color Purple and Sara Bareilles.