Twenty-three others were injured, and the two shooters -- Dylan Klebold and Eric Harris -- killed themselves.

CNN: Columbine seniors graduate under the shadow of shooting

Many people have asked why the parents of Littleton gunmen Eric Harris, 18, and Dylan Klebold, 17, didn't know that their teen-agers were making homemade bombs and doing other preparations for the assault.

CNN: Town meeting looks at lessons from Littleton

Eric Varvel is the boss of Credit Suisse's investment bank, Harris Simmons heads Zions Bancorporation, a more local bank, and Allan O'Bryant runs the Japanese arm of Reinsurance Group of America.

ECONOMIST: Schumpeter