The three-day meeting of the Democratic National Committee, held to welcome new members and start building the 2028 primary calendar, was the first under new chair Ken Martin.... The party, Martin vowed, was now bringing “a bazooka to a knife fight,” and would no longer “play by the rules” if Republicans broke them.
I'm guessing Martin deployed his "a bazooka to a knife fight" metaphor — in Minneapolis — before the the shooting of children that took place nearby.
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Bazooka (Wikipedia):The name "bazooka" comes from an extension of the word bazoo, which is slang for "mouth" or "boastful talk"...
That's fitting, for politicians.
During World War II, "bazooka" became the universally applied nickname of the new American anti-tank weapon, due to its vague resemblance to the musical instrument invented and popularized by 1930s American comedian Bob Burns.

UPDATE: In the comments below, Olson Johnson is right! observes that Semafor has taken Walz's words out of context: