Israel behind pager explosions, sources say, as Hezbollah vows 'reckoning'

Israel was behind the deadly explosion of pagers across Lebanon on Tuesday, sources told ABC News on Wednesday.

At least 12 civilians were killed and more than 2,750 people injured in the explosions, according to Lebanese authorities. Around 200 of the injuries were critical and required surgery, the Lebanese Ministry of Public Health said.

The civilians killed include an 8-year-old girl and an 11-year-old boy, according to Lebanese Health Minister Firass Abiad.

The Hezbollah militant group said it is conducting a "security and scientific investigation" into the explosion of pagers across Lebanon on Tuesday.

Hezbollah said 11 of its members were killed on Tuesday, though -- as is typical in its statements -- did not specify how they died.

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"We hold the Israeli enemy fully responsible for this criminal aggression, which also targeted civilians and led to the deaths of a number of martyrs and the injury of a large number with various wounds," Hezbollah said of the pager explosions in a Tuesday statement.

In a Wednesday morning statement, Hezbollah said it would continue operations to "support Gaza," and vowed a "reckoning" for Israel for the "massacre on Tuesday."

The dead and injured included people who are not members of Hezbollah, such as a 10-year-old girl killed in the eastern village of Saraain, according to Hezbollah-owned Al-Ahed News.

Israel has not commented on its alleged involvement in the apparent attack, which prompted chaos in the capital Beirut and elsewhere in Hezbollah's south Lebanon heartland.

Around 100 hospitals received wounded people, the Lebanese Ministry of Public Health said, with hospitals in Beirut and its southern suburb quickly filling to capacity. Patients were then directed to other hospitals outside the region.

Most of the injuries were to the face, hand or abdomen, officials said.

The Iranian ambassador to Lebanon, Mojtaba Amani, was among those who had one of the pagers and was injured in an explosion Tuesday, according to Iranian state TV. The diplomat said in a phone call that he was "feeling well and fully conscious," according to Iranian state TV.

At least 14 people were also injured in targeted attacks on Hezbollah members in Syria, according to the Syrian Ministry of Foreign Affairs.

The alleged Israeli operation has again piqued fears of escalation in the Israel-Hezbollah conflict ongoing since Oct. 8, when members of the Iranian-backed group began cross-border attacks in support of Hamas' war with Israel in the Gaza Strip.

Frontier skirmishes, Israeli strikes and Hezbollah rocket and artillery salvoes have been near-constant through 11 months of war in Gaza. Israeli officials have repeatedly threatened to launch a new military operation against Hezbollah along the Israel-Lebanon border. Tens of thousands of Israelis have left their homes in border regions due to the fighting.

The Israel Defense Forces said warplanes hit Hezbollah targets in six locations in southern Lebanon overnight into Wednesday. Artillery strikes were also conducted, it added.

Hezbollah leader Hassan Nasrallah is due to make a public address on Thursday afternoon to address the situation. In February, Nasrallah urged members to stop using their cell phones, describing the technology as "a deadly agent."

Schools across Lebanon will be closed on Wednesday, Lebanese state media reported, citing the country's Minister of Education. Schools and offices closed include public and private schools, high schools, technical institutes, the Lebanese University and private higher education institutions, Lebanese state media reported.

The Lebanese Council of Ministers collectively condemned "this criminal Israeli aggression, which constitutes a serious violation of Lebanese sovereignty and a crime by all standards."

It added that "the government immediately began making all necessary contacts with the countries concerned and the United Nations to place it before its responsibilities regarding this continuing crime."

The United Nations special coordinator for Lebanon condemned the attack on Lebanon, calling it an "extremely concerning escalation in what is an already unacceptably volatile context," in a statement released by the U.N. Office of the Spokesperson for the Secretary General.

U.S. officials said Washington, D.C. had no role in -- or pre-knowledge of -- the apparent attack. State Department spokesperson Matthew Miller said the administration was "gathering information" on the incident.

Both Miller and White House press secretary Karine Jean-Pierre declined to speculate on whether Israel was responsible.

The U.S. and the European Union have both designated the Hezbollah militant group a foreign terrorist organization.