ISIS claims responsibility for London tube attack

The Islamic State militant group, which has said it was behind several attacks on Western cities in recent years, including two attacks in London and one in Manchester this year, claimed responsibility for Friday's bomb attack in London's underground system through its news agency, Amaq.

A home-made bomb on a packed rush-hour commuter train in London engulfed a carriage in flames and injured 29 people on Friday, but apparently failed to fully explode, in Britain's fifth major terrorism incident this year.

Prime Minister Theresa May called the incident a "cowardly attack" and said the national threat level had been raised a notch to its highest level, "critical."