Oklahoma City

A truck with two and a half tonnes of fertiliser and fuel oil was parked under the daycare windows on the north side of the Alfred P. Murrah Federal Building and went off at two minutes past nine, when the offices had just opened.

A third of the building came down. A hundred and sixty-eight were killed, including nineteen children in the America's Kids daycare on the second floor. Most of the children had been dropped off within the previous twenty minutes.

People came from every direction. Rescuers went into a building that was still falling and worked in the rain for weeks.

Rebecca Anderson, a registered nurse, drove to the site on her own from her house, went in to help and was struck on the head by falling debris. She died four days later - the only rescuer killed, and a civilian who had simply gone.

The survivor tree, an American elm in the car park that had been scorched and shredded, was kept and is still there.