At least twelve people were killed and thousands more were injured after a number of handheld pagers exploded across Lebanon on Tuesday, the country's Health Ministry said.
Lebanese Health Minister Firas Abiad said the blasts "killed eight people, including a girl."
"About 2,750 people were injured... more than 200 of them critically," he added.
Hezbollah, a political organization in Lebanon, said at least two of its members were killed.
Iranian-backed Hezbollah blamed Israel for the explosions. Israel did not immediately comment on the incident.
"We hold the Israeli enemy fully responsible for this criminal aggression," Hezbollah said.
It added that Israel "will certainly receive its just punishment for this sinful aggression."
A Hezbollah official, speaking on the condition of anonymity, told the Reuters news agency that the incident was "the biggest security breach" the group had been subjected to in nearly a year of conflict with Israel.
Reports that Israel targeted the communications devices and was behind the detonations remain unconfirmed.
A Hezbollah official, speaking to Associated Press on condition of anonymity because he was not authorized to speak to the media, said the explosions were the result of "a security operation that targeted the devices."
"The enemy [Israel] stands behind this security incident," the official said, without elaborating. He added that the new pagers that Hezbollah members were carrying had lithium batteries that apparently exploded.
According to the German DPA news agency, the Bahman hospital in Beirut received more than 100 people. Some were said to be in critical condition.
The Lebanese Health Ministry urged all hospitals across the country to be on alert. It also advised people to stay clear of devices that might pose a threat.
"The Ministry requests all citizens who own wireless communications devices to stay away from them until the truth of what is happening is revealed," the ministry said in a statement.
Iran's Mehr news agency reported that the Iranian ambassador to Lebanon, Mojtaba Amani, was among those injured.
Hezbollah is considered a terrorist organization by the US, Germany and several Sunni Arab countries, while the EU lists its armed wing as a terrorist group. It also operates as a major political party within Lebanon.
