Agreed, although if you add enough qualifiers, *any* shooting can be made to sound "unique" and original, or the "most deadly".
Charles Whitman (The UT Austin sniper) had three rifles, three pistols, a shotgun and a machete, killed 16 people and injured 32. And that was 33 years before Columbine.
Columbine wasn't the "most deadly" school shooting, unless you qualify it as the "most deadly high school shooting". So that's exactly what the media did. Talk about grasping for superlatives - that's the media's stock-in-trade.