My brother Yoram spotted him first, but a split second later I saw him too. He was small, like a child -- he can't have been more than 17 -- and he was wearing a big smile. It was a sinister rather than a happy smile, the smile of someone whose mind has been skewed by drugs.

As he reached the cafe door, I could see he was hiding something underneath his shirt. Yoram shouted, but it was too late. There was an ear-splitting noise and a blinding light, then darkness, silence and a smell I cannot describe: the reek of shredded, burning flesh. I had been standing at the front of the cafe, behind a pillar. Yoram had been outside by one of the pavement tables. As I looked up, the floor-to-ceiling glass that separated us was cascading like a waterfall. I looked down. Incredibly, thanks to the pillar, I appeared to be unharmed. Then I looked right and left and, through dense, black smoke, I saw things that no one should see....