WATCH: Jake Tapper confronts Broward County sheriff in heated interview over his agency's failures

CNN anchor Jake Tapper grilled Broward County Sheriff Scott Israel on CNN's "State of the Union" Sunday over his agency's alleged failings in responding to the tragic shooting at Marjory Stoneman Douglas high school on Feb. 14.

On his department's response:

Tapper began the lengthy interview by asking Israel numerous questions about his department's response to the shooting. Israel confirmed the school resource officer didn't act as he should have, which is the reason the department was moving to fire him before he chose to resign.

Tapper also questioned Israel over reports that other Broward County sheriff deputies arrived at the school and also chose to do nothing. Israel dodged most of the questions, saying he can't discuss them because his department is in the midst of an investigation.

"We are feverishly dissecting, it's a voluminous investigation, we're taking hundreds and hundreds of statements," Israel said. "And right now, Jake, the focus of this agency is on the successful prosecution of the killer."

Israel promised that his department is looking at the actions of every single officer and supervisor to determine if there was any "dereliction of duty." If there was, Israel vowed to "take care of business" — his phrasing for termination.

On when he found out his deputy didn't engage shooter:

This question was important because Israel lectured NRA spokeswoman Dana Loesch at a CNN town hall last week alleging she and the NRA haven't been "standing up" and protecting school kids. Tapper pointed out it would be very hypocritical for Israel to lecture the NRA and say law enforcement needs more resources when his agency failed to act and protect the children.

Israel said he learned about his deputy's dereliction of duty before the town hall but didn't mention it then because he wanted to make sure the information was corroborated.

"We needed to dot I's and cross T's and I would certainly not disclose it to a family at a town hall," the sheriff explained.

On whether medical personnel was told to stand down:

An EMS first responder told WSVN-TV that medical first responders were told to wait outside the school and not attend to victims so law enforcement could clear the building. The anonymous man said lives could have been saved if they weren't prevented from going inside the building.

"That's very accurate," Israel said.

However, he denied the allegation that EMS responders were prevented from entering the building.

On the missed red flags:

There were at least 18 calls to the Broward County sheriff's department about the school shooter. Israel said his department handled all but two of them correctly, and they are looking into the other two. However, he said he doesn't believe there was anything his employees could have done differently.

But Tapper wasn't satisfied with that answer.

"Sir, isn't making a threat against a school a crime?" Tapper asked.

"If the person doesn't have the apparent ability to carry it out, it's not a crime," Israel shot back.

Responding to claims that just three months ago an anonymous tipster called the Broward County sheriff's department and reported the shooter was a "school shooter in the making," Israel said he would have to review the incident.

"And we are — that's an active internal investigation. And we are looking in to it," he said.

On taking responsibility for multiple failures:

Tapper asked: "Are you really not taking any responsibility for the multiple red flags that were brought to the attention of the Broward Sheriff's Office about this shooter before the incident, whether it was people near him, close to him calling the police.."

"Jake, I can only take responsibility for what I knew about. I exercised my due diligence. I have given amazing leadership to this agency," Israel shot back.

"Amazing leadership?" questioned, very confused.

"Yes, Jake," Israel replied.

Then Tapper tore into Israel:

Maybe you measure somebody's leadership by whether or not they protect the community. In this case, you have listed 23 incidents before the shooting involving the shooter, and still nothing was done to keep guns out of his hands, to make sure that the school was protected, to make sure you were keeping an eye on him.

Your deputy at the school failed. I don't understand how you can sit there and claim amazing leadership.

On whether Israel will resign:

Thousands of people have called on Israel to resign after the revelations and failures of his department were made public. Tapper asked if Israel planned to resign — and Israel's answer was unequivocal.

"Of course I won't resign," he said.

Then Tapper finally had enough:

For his last question, Tapper asked Israel if the shooting would have been prevented had the Broward County sheriff's department acted differently.

"Listen, ifs and buts and candy and nuts, O.J. Simpson would still be in the record books," Israel said in response.

"I don't know what that means," Tapper shot back. "There's 17 dead people, and there's a whole long list of things your department could have been done differently."

Watch the interview below: