LONDON, May 23 (Reuters) - British police said that at least 19 people were killed and 50 others injured in a blast at a music venue in the northern English city of Manchester, and said that they were treating it as a "terrorist incident".

"So far 19 people have been confirmed dead, with around 50 others injured. This is currently being treated as a terrorist incident until police know otherwise," Greater Manchester Police said in a tweet.

The incident happened at the end of a gig by U.S. singer Ariana Grande.

(Reporting by Kate Holton; writing by Alistair Smout; Editing by Guy Faulconbridge and Sandra Maler) ((alistair.smout@thomsonreuters.com; +44 207 542 7064; Reuters Messaging: alistair.smout.thomsonreuters.com@reuters.net))