AMNA NAWAZ: Welcome to the "News Hour."

It was an unprecedented and shocking attack.

All across Lebanon today, pagers used by members of the militant group Hezbollah exploded.

Lebanon's Health Ministry says 2,700 people were injured and nine were killed, including a young girl.

Hezbollah blamed Israel for the attack.

Israel has not made any public statement.

GEOFF BENNETT: It comes as tensions between Israel and Lebanon have been near boiling for almost a year since just after the October 7 Hamas terror attacks on Israel.

Days later, Hezbollah stepped up fire into Northern Israel.

The two sides have had near-daily exchanges of artillery and rocket fire since forcing thousands to flee.

Nick Schifrin is here with more.

So, Nick, walk us through your reporting and tell us more about what happened.

NICK SCHIFRIN: Geoff, experts I spoke to all day describe this attack as audacious, never seen before anywhere and an almost unbelievable scale.

And you can really see that even from the videos that immediately come out, Lebanese Hezbollah members in markets going about their days.

All of a sudden, the pagers they're wearing on their belts -- you see that in a market there -- or in their pockets or bags exploded.

Pagers in Syria exploded too.

And that led to 2,700 wounded, as you said, hundreds of them serious.

So the expectation tonight is the total death toll and the total wounded toll will increase, Geoff.

So what happened?

Officially, we do not know.

As you said, Hezbollah blamed Israel.

I asked an Israeli official about that.

The only response I got was an emoji of a shrugged shoulders.

So that's what Israel is saying, nothing.

The experts I speak to, though, do believe that Israel conducted this attack.

And they believe the most likely scenario is that the pagers were altered to include small explosives.

And that means the supply chain of the pagers were compromised by some entity that wanted to do damage to Hezbollah.

Experts also tell me that, a few months ago, Hezbollah switched over from cell phones to pagers, thinking that there would be less surveillance by Israel.

Obviously, that backfired.

GEOFF BENNETT: Well, how much of a blow is this to Hezbollah?

NICK SCHIFRIN: It's a big blow; 2,700, as you said, is a lot of people, not aimed at the leadership, not even at the hardcore militants.

Experts tell me it was actually aimed at the mid-level members of Hezbollah.

It also means that it affected thousands of families in Southern Beirut and Southern Lebanon.

That will put a lot more pressure on Hezbollah to respond.

It's extremely embarrassing, in the words of one expert, a slap in the face to the leaders, demoralizing to supporters, raises real questions, of course, about the group's security and, depending on where these pagers are from, Iranian security as well.

Israel recently struck Fuad Shukr.

That is Hezbollah's number three in southern Beirut.

And so, again, that just leads to the idea, the feeling among Hezbollah right now that Israel can get anyone anywhere.

GEOFF BENNETT: Well, as we said, tensions are extremely high.

And this follows political announcements by the Israeli government.

Put that into context for us.

NICK SCHIFRIN: Yes, the timing here is very interesting.

At 5:00 in the morning Israel time, Israel's security cabinet released a statement that added a goal to their official war aims in Gaza - - quote -- "returning the residents of the war securely to their homes," a reference to the 60,000 Northern Israelis who have been internally displaced since the October 7 Hamas attack and October the 8th, when Hezbollah opened fire.

Now, that came a few hours after Yoav Gallant, Israel's defense minister, declared that U.S.-led diplomatic efforts to try and de-escalate between Israel and Hezbollah were dead.

Gallant said - - quote -- "The only way left to return the residents to the north to their homes is via military action."

Now, that was a readout of Gallant's meeting with U.S. diplomats that he was meeting yesterday to try and de-escalate - - de-escalate tension,Well, Amos Hochstein, who's a special adviser to the president.

And a senior adviser -- senior administration official told me that Hochstein's message was this.

Hochstein cautioned them that the U.S. does not believe a broader conflict in Lebanon achieves the goal of returning residents to their home in the north.

It risks a much broader and protracted regional conflict.

Hochstein made this clear to Israeli officials and the U.S. remains committed to a diplomatic solution.

That was yesterday, Geoff, in those meetings.

Today, the fear of escalation is very high.

GEOFF BENNETT: So, based on your reporting, where might all of this lead?

NICK SCHIFRIN: So some of the experts, I believe -- some of the experts spoke to I spoke to said that they believe that Israel is trying to message that Israel is serious about Northern Israel, the residents who are no longer in their homes, Hezbollah is overreaching, and that this was a message to accept the diplomatic terms that Hochstein has been trying to get them to accept, which is essentially moving Hezbollah fighters about six miles away from the Lebanon-Israel border behind the Litani River.

The hope in this analysis is that Hezbollah doesn't want war, it can't afford it politically in Lebanon, and also Iran doesn't want Hezbollah to go to war with Israel because Hezbollah is Iran's best deterrent.

But Lebanese analysts and other experts I speak to, Geoff, say, no way, that this is so embarrassing to Hezbollah, it will cause an escalation.

Hezbollah has to respond in a violent way, in a different way than it has in the past, and that could lead to Israel doing the same and a cycle of escalation, the very cycle the U.S. is trying to avoid.

GEOFF BENNETT: Nick Schifrin, thank you so much for walking us through all of this.

We appreciate it.

NICK SCHIFRIN: Thank you.