AMNA NAWAZ: Five days after a mass shooting at Brown University left two students dead and nine others injured, authorities have not yet identified a suspect and the shooter remains at large.

Providence Mayor Brett Smiley acknowledged that many in the city remain restless and eager for an arrest.

Yesterday, the FBI released these images of a person of interest seen in the area moments before the attack.

Today, Providence police released these photos asking for the public's help to identify a man they say was in proximity of the person of interest.

For one family, this shooting was a harrowing reminder of another traumatic incident, the attempted assassination of Louisville Mayor Craig Greenberg in 2022.

The mayor's youngest son, Ben Greenberg, is a junior at Brown University.

And both join me now.

Gentlemen, welcome to the show.

Thank you so much for joining us.

BEN GREENBERG, Brown University Student: Thank you.

CRAIG GREENBERG (D), Mayor of Louisville, Kentucky: Our pleasure to be here.

AMNA NAWAZ: So, Ben, I want to begin with you.

It's my understanding your apartment at Brown is across the street from where the shooting unfolded.

Just tell us how and when you realized what was unfolding and what you and your friends did when you realized that.

BEN GREENBERG: Yes, so I live across the street from Barus and Holley in a house.

It's a two-unit house, but it's essentially a house.

So I just got back from the gym and I was in my room.

And my friend texted me.

He's like: "What are all these sirens doing?"

He, like, makes a joke about, like, what's going on, just not knowing it's anything serious.

And we come -- we get a DPS notification from Brown saying there's an active shooter.

And all of my friends go to my roommate's room.

We barricade ourselves in the room, because we have a back door to the other unit that doesn't lock.

And we didn't know -- we didn't know really anything at the time and we're all pretty stressed if maybe the shooter could have theoretically gone in.

So we barricade ourselves in a room and stay the night all together.

AMNA NAWAZ: Ben, I'm so sorry for what you have had to endure.

And I have to ask your father here, Mr.

Mayor, take us back to the moment you learned about the shooting.

And having lived through what you did yourself in an attempt on your life, surviving gun violence, what did you think in the moment when you realized what your son was going through?

CRAIG GREENBERG: My heart sank.

You become physically numb in those types of moments.

My wife and I were at a University of Louisville basketball game when I got the -- we're up for alerts from Brown University as well.

So it immediately came in, and immediately reached out to Ben to see if he was safe.

And Rachel and I left the game shortly after we knew how serious it was, so we could stay in touch with Ben for the entire evening.

But it took us right back to Valentine's Day of 2022, when there was an assassination attempt on me in my campaign office.

It took me back to my time as mayor, when there was a mass shooting in April of 23, shortly after I became mayor here in Louisville, and then another one a few days later in one of our parks, which was a horrible week for our city.

But I have never experienced it before as a father.

And so Rachel and I had a long night staying on the phone and in constant touch by text with Ben and his roommates, answering questions, providing reassurance and just talking through things, given the stress, while we were all waiting for answers.

AMNA NAWAZ: Ben, I have to assume you're part of a generation that grew up going through lockdown drills in schools, like so many other kids in this country.

You are familiar with gun violence in terms of having witnessed what your father has been through himself.

Did you ever think something like this would happen?

Did you feel prepared when you realized what was unfolding?

BEN GREENBERG: That was one of the first things I talked to my friends about.

We were saying, really, it doesn't -- you see so many bad things on the news and you really don't think any of that stuff is going to happen to you personally until it does.

And especially this being the second time - - I haven't been actively -- thankfully, like, physically unharmed from any acts of gun violence, but this being the second time is just really -- I think multiple people are Brown, this has been their multiple occurrences with gun violence.

It's really sad that it's becoming - - it feels like it's becoming so commonplace.

AMNA NAWAZ: And are you worried about returning to campus?

BEN GREENBERG: Well, thankfully, I'm going abroad next semester.

So I think it'll be really nice to take a break from campus.

But one of my best friends -- I have a group of friends all going abroad, and I have one of them who's staying at campus.

And I really feel for him with the increase in security, especially one of my friends who was in the building at the time.

He's an engineering student, so he's always there 24/7.

And, really, how are you going to be in that building to do work, let alone to take finals in that building again?

So, heart really goes out to those students as well.

AMNA NAWAZ: Mr.

Mayor, of course, you have navigated these moments personally, also as a leader in your city.

And you recently announced you're taking some additional security measures in Louisville after what we saw was the targeted terrorist attack, another mass shooting in Australia, that one targeting members of the Jewish community there.

Tell us a little bit about why you're taking those steps and why now.

CRAIG GREENBERG: Well, we have to remain vigilant, whether it's in Providence, in Louisville, all across the country, particularly when it's around religious gatherings or political gatherings.

Fortunately, last night, our community menorah lighting went off without any incidents.

And we will continue -- people - - I want people to continue to live their lives.

I want everyone here in Louisville, everyone all across the country to feel safe when they're doing that, particularly when they're practicing their religion.

And so we are always vigilant about that with our police department.

We share a lot of intelligence with others around the country.

And we are doing everything we can to make sure that people in Louisville feel safe and are safe.

AMNA NAWAZ: Can I just ask you both briefly, your family has been through so much personally now in the last three or four years, having survived two different incidents of gun violence.

What is it you would say that you want to see happen to make sure that this doesn't happen to any other family?

Mr.

Mayor, I will begin with you.

CRAIG GREENBERG: I'd love to see some steps at the federal level, even if they're just small steps.

I understand the politics of issues around guns, but let's take some small steps to say, everyone, regardless of what political party you are, we all want to reduce the amount of gun violence.

So let's take some steps that we know the American people support.

American people support background checks for everyone who's buying a gun.

They support waiting periods.

We all wait right now at this holiday season.

We all wait to get the products and gifts that we have purchased in the mail.

Or even, when you're using Amazon Prime, there's still a little bit of a waiting period.

The same should be true for guns.

Let's ban got Glock switches in even more states that convert legal firearms into illegal automatic weapons.

Let's ban the use of 3-D printers to make guns.

Let's support more mental health initiatives.

There's so much that can be done.

I'd love to see Congress take some steps, even if small steps, to show this country that we're serious about cracking down on gun violence.

AMNA NAWAZ: Ben, I will give you the final word here.

What would you say?

BEN GREENBERG: I just hope that the -- Americans aren't becoming normalized to gun violence because, it really can happen to anyone.

Especially when you're so close geographically and really knowing people who have been affected, it makes you realize that it can be anyone.

And we're really just -- I'm so fortunate to be OK, that my dad's OK.

But I really hope that the American people knows that this is not OK and cannot be normalized.

AMNA NAWAZ: That is Louisville Mayor Craig Greenberg and his son Ben joining us tonight.

Thank you to you both.

We really appreciate your time.

CRAIG GREENBERG: Thank you.

BEN GREENBERG: Thank you.