Donald Trump slammed former President George W. Bush for the 9/11 attacks happening "during his reign" in an interview aired Friday, prompting a strong rebuke from a certain GOP presidential rival.

Asked by Bloomberg's Stephanie Ruhle if he could reassure the American people in times of crisis, as when Bush stood before the nation in the aftermath of the deadliest terror attack in its history or when President Barack Obama mourned the Sandy Hook shooting in 2012, Trump was adamant.

“I think I have a bigger heart than all of them," Trump responded. "I think I’m much more competent then all of them. I mean, say what you want, the World Trade Center came down during his time.”

Ruhle interjected: “Hold on, you can’t blame George Bush for that."

“He was president, OK? Don’t blame him or don’t blame him, but he was president," Trump continued. "The World Trade Center came down during his reign. If you look at Sandy Hook, those people are still begging for help."

The United States needs a leader, he said, as government "has proven to be a disaster" under the Obama administration.

Jeb Bush hit back at the remark later in the day on Twitter, writing, "How pathetic for @realDonaldTrump to criticize the president for 9/11. We were attacked & my brother kept us safe."

Late Friday, Trump responded on Twitter by calling Bush "pathetic" back. "No @JebBush, you're pathetic for saying nothing happened during your brother's term when the World Trade Center was attacked and brought down," he tweeted.

A spokesman with George W. Bush's office declined comment to POLITICO and to the Daily Mail.