My own leadership lesson from 9/11: When it's crunch time, leaders act.
On that day, President Bush took immediate steps to secure the country and pursue the terrorists responsible. Mayor Gulianni immediately took charge of the rescue efforts and acted to calm a panicked city. All across the nation, local leaders did what was needed to secure their communities against a very vague threat. I was one of those, working with authorities at the state level to guard nuclear power plants, bio-labs and key infrastructure.
When the world seems to be falling apart, action is vital for a few reasons.
1. It gives people something to do. Idle people fret; active people focus.
2. It gives people hope. Inaction suggests there's nothing that can be done - that's hopelessness.
3. It prevents people from acting independently. If the leader doesn't act, someone will step up to lead, or many people will strike out on their own with uncoordinated and sometimes conflicting efforts.
The risk: To be decisive in times of crisis means you have act before you know everything. The best places to start are gathering information (send people to check, task them with fact-finding) and taking care of people (make sure everyone is OK, and that worries about their families are calmed as well).
Bottom line: The first thing people think when disaster strikes is "What do we do?" And the first place they look is to the leader.