PBS journalist Gwen Ifill moderated the 2008 vice-presidential debate in St. Louis. (Don Emmert/Getty Images)

News that PBS journalist Gwen Ifill has died shook the media on Monday and triggered an outpouring of tributes on Twitter, where reporters remembered the two-time vice-presidential debate moderator as a kind and talented pioneer.

Many journalists described Ifill, who died of cancer at 61, as a role model for women of color in the press and a beacon of professionalism for all.

“Gwen was one of America's leading lights in journalism and a fundamental reason public media is considered a trusted window on the world by audiences across the nation,” PBS chief executive Paula Kerger said in a statement. “Her contributions to thoughtful reporting and civic discourse simply cannot be overstated. She often said that her job was to bring light rather than heat to issues of importance to our society. Gwen did this with grace and a steadfast commitment to excellence.”

Ifill and PBS colleague Judy Woodruff moderated a Democratic primary debate in February. She took a leave of absence in April for undisclosed health reasons, but returned the next month. PBS said the week before Election Day that Ifill would once again take a leave and would be unable to anchor election-night coverage.