(CNN) A bipartisan quartet of high-profile senators said Sunday that "recent reports of Russian interference in our election should alarm every American," as President-elect Donald Trump sharpened his unprecedented attacks on US intelligence agencies.

The group -- two Republicans and two Democrats -- called for an investigation into American intelligence agencies' conclusion that Russian hacking was intended to help Trump defeat Hillary Clinton.

"Congress's national security committees have worked diligently to address the complex challenge of cybersecurity, but recent events show that more must be done," said Sens. Chuck Schumer, the incoming Senate Democratic leader, Sen. John McCain, the Armed Services Committee chairman, fellow Republican Sen. Lindsey Graham, and Sen. Jack Reed, the top Armed Services Committee Democrat, in a Sunday morning statement.

"While protecting classified material, we have an obligation to inform the public about recent cyberattacks that have cut to the heart of our free society. Democrats and Republicans must work together, and across the jurisdictional lines of the Congress, to examine these recent incidents thoroughly and devise comprehensive solutions to deter and defend against further cyber-attacks."

The letter is an implicit rebuke of Trump, who has questioned whether Russia actually interfered with the election, including with hacks of Democratic operatives. The President-elect on Sunday morning blasted the intelligence community anew, calling its assessment that Russia interfered in the election "ridiculous."

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