Prince William and Princess Kate Pay Respects to Orlando Nightclub Shooting Victims

The royals signed a condolence book at the U.S. Embassy in London today.

LONDON -- The Duke and Duchess of Cambridge honored the victims of the mass shooting at a gay nightclub in Orlando, Florida, which killed 49.

Prince William and Princess Kate signed a condolence book at the U.S. Embassy in London today. The message reads: "With our deepest condolences and with our thoughts and prayers to all those affected -- William and Catherine."

The couple also met the U.S. ambassador and a small group of embassy staff, including representatives from the U.S. Embassy's LGBT network, GLIFAA.

Later today the duke and duchess will travel to Northern Ireland to attend a garden party at Hillsborough Castle. The secretary of state for Northern Ireland hosts the annual event and each year a member of the royal family attends. Queen Elizabeth II and Prince Philip were the guests of honor in 2014 during their trip to Northern Ireland. Around 2,500 guests are invited each year, drawn from a wide cross-section of Northern Ireland society, including the voluntary and community sectors, local charities, youth organizations and wider civil society. Hillsborough Castle is the official residence of the royal family when they are in Northern Ireland and the home of the secretary of state since the 1970s.