Celebrities flooded Twitter on Monday with condolences for those affected by the deadly blast at an Ariana Grande concert in Manchester, England, earlier in the evening.

Police said at least 19 people were killed and about 50 were injured in what they were treating as a terrorist incident. A witness told the BBC that as many as 30 people could be seen lying on the ground at the Manchester Arena concert venue, Europe’s largest indoor arena with a capacity for 21,000 people.