The Economist has a short but great overview on crisis management. The article is well worth reading completely, but there is one section that bears highlighting:

Be well prepared in advance. Potential members of a crisis management “team” should rehearse how they would manage the impact of an incident. It is a bit like learning the safety instructions on a plane before take-off: you hope you will never need them, but you know it would be unwise to miss the lesson. The team should include the chief executive and a representative of the press office. Thereafter, all external enquiries relating to a crisis should be answered by the team.

It's amazing how often this step gets left out of business continuity plans and it is probably the most important. I heartily encourage all executives to not just plan but practice practice practice. This is the sort of thing that can really bite you hard at just the wrong time.