New York, United States: US pop star Ariana Grande late Monday said she felt at a loss for words after a suspected terror attack at her concert in the British city of Manchester.

‘Broken,’ she wrote in her first reaction on Twitter.

‘From the bottom of my heart, I am so so sorry. I don’t have words,’ she wrote.

Police said at least 19 people were killed and around 50 wounded in the attack at the 21,000-capacity Manchester Arena.

It was the deadliest attack in Britain since 2005.

Grande, a 23-year-old former child star, is not known for her political views and draws an audience of teenagers and pre-teenagers.

Two U.S. officials have told Reuters on condition of anonymity that initial signs pointed to a suicide bomber as being responsible for the bombing.

Grande was performing in Manchester during the European leg of a concert tour to support her latest album, ‘Dangerous Woman.’

She was scheduled to perform at London’s O2 arena on Thursday and then in Belgium, Poland and Germany in the coming weeks. It was not immediately clear whether those concerts would go forward following Monday’s attack.

Grande, who starred in the Broadway musical ‘13’ and on the Nickelodeon TV series Victorious before releasing her solo debut album, is credited with having an exceptionally broad vocal range for a pop star.

She is best known for her singles ‘Problem,’ and ‘Break Free’ from her sophomore album, My Everything.