Queen Elizabeth II held a moment of silence on Tuesday for the 22 victims killed in the attack at an Ariana Grande concert in Manchester, U.K.
The queen stood at the top of the steps at Buckingham Palace with her husband Prince Philip, her son Prince Charles and his wife Camilla, before attending a garden party. The national anthem played during the moment to honor the victims.
Earlier in the day, Queen Elizabeth II thanked emergency services in Manchester for responding to the explosion and expressed her condolences.
"I know I speak for everyone in expressing my deepest sympathy to all who have been affected by this dreadful event and especially to the families and friends of those who have died or were injured," the queen said in a statement.
"I want to thank all the members of the emergency services, who have responded with such professionalism and care."
A bomb exploded at the end of Grande's concert Monday night, sending concertgoers into a panic as they rushed out of the packed Manchester Areana. Police said they were treating the attack as a "terrorist incident," and the Islamic State has claimed responsibility.
At least 22 people died, including an 8-year-old girl. At least 59 people were hurt, including 12 children under 16 who were rushed to the hospital with "serious injuries."
British Prime Minister Theresa May called it "a callous terrorist attack." She added, "We struggle to comprehend the warped and twisted mind that sees a room packed with young children not as a scene to cherish but as an opportunity for carnage."
May and her opponent, Labor leader Jeremy Corbyn, suspended their campaigns for the upcoming election in the wake of the tragedy.