hmm
David Sonboly: Air France Flight 422 crash, 53 killed
Adam Lanza: 1992 Guadalajara explosions, Paris Valley Airport plane crash
Eric Harris: USS George Washington/Nissho Maru collision
Brenda Spencer (not a mass killer): Beau-Fraisier, Algiers, terrorist attack, 9 killed.
Charles Whitman: end of the Battle of Merdjayoun during the Syria-Lebanon campaign during World War 2, sinking of the Brockley Hill cargo ship by a German submarine U-651. Interestingly enough, he also shared the same birthday (June 24th) with another sniper from the 60s, Michael Andrew Clark, but Clark was born in 1948.
Michael Andrew Clark: born on the day the Berlin Blockade began
me: pirates stealing a ship