King Charles has issued a personal message expressing his grief over the catastrophic flash floods that struck Nepal this week. As of Thursday, more than 350 people have been killed and approximately 1,000 remain unaccounted for, including at least 700 foreign tourists who were trekking in the area at the time the disaster occurred, according to Reuters. The flooding appears to have been triggered by a glacier collapse, and rescue teams are using helicopters to reach communities cut off by the destruction.

“My wife and I are heartbroken to hear of the devastating flooding that has struck the Nepal-China border,” the King wrote. “Many in the United Kingdom have strong, deep and personal ties to this part of the world. We send our most profound sympathy to all those who have so tragically lost their loved ones and we feel deeply for the many families awaiting anxiously the news of friends and relations.” At least 33 British nationals are among those missing, according to the BBC. Dozens of American and Canadian tourists have been reported missing as well.

“Our hearts go out also to the families of all the police and Armed Forces personnel who lost their lives while carrying out their courageous duty in the service of others and we give our deepest thanks to those who have responded so selflessly in undertaking rescue efforts,” the statement continued. Charles also wrote that the UK “stands ready to help support those in need.” Prime Minister Andy Burnham has since announced a pledge of £5 million ($6.6 million) and an offer to deploy emergency responders to Nepal.

The Prince and Princess of Wales similarly shared their concerns for first responders. “The scale of the devastation along the Nepal-China border is shocking. We are thinking of everyone caught up in this terrible disaster,” the couple wrote in a statement. “Our thoughts are especially with the families facing an unbearable wait for news and with the communities confronting such immense loss. We are incredibly grateful to all those working in such dangerous conditions to rescue people and support those affected.”

The Dutch royal family also expressed their condolences. King Willem-Alexander and Queen Máxima released a statement saying: “The devastating effects of the flooding in Nepal are becoming ever more apparent. Many families now find themselves mourning loved ones or anxiously waiting for more news. Our thoughts are with them, as well as with everyone involved in rescue efforts and providing assistance.”