1. The Islamic State claimed responsibility for the crude bomb that exploded on a crowded train in London this morning, leaving 29 injured. It was the fifth terrorist attack on Britain this year.

There has been longstanding concern that militants would target the London Underground, known as the Tube, as they did in 2005. The government raised the national threat level one notch to “critical,” the highest.

“This is terrifying and a reminder it can happen anywhere,” said one woman who was on the train. “Nowhere is safe.”