Communications with Hezbollah's head Hassan Nasrallah were halted after Israel's unprecedented strikes on the southern suburbs of Beirut on Friday, a source close to the group said.
Hours after the strikes, Hezbollah had not made a statement on his fate. A source close to Hezbollah told Reuters Nasrallah was alive and Iran's Tasnim news agency also reported he was safe. A senior Iranian security official told Reuters Tehran was checking his status.
Israeli warplanes launched 10 airstrikes on the southern suburb, which is regarded as a Hezbollah stronghold, and a large smoke plume was seen over the area later.
Shortly after the strikes, Israeli army spokesman Daniel Hagari claimed the attack targeted Hezbollah's main headquarters, which he claimed was built underneath civilian buildings.
Lebanon's Health Ministry reported that six people were killed and dozens of others were injured as a result of the strikes.
Nasrallah has been in hiding for years, very rarely appearing in public. He regularly gives speeches, but always by video from unknown locations. The site hit Friday evening had not been publicly known as Hezbollah's main headquarters.
Israel has pounded Lebanon since Monday morning, killing over 700 people and injuring nearly 2,200 others, according to figures released by the Lebanese Health Ministry.
The ministry also said that the death toll in Lebanon since last October is 1,540, in addition to more than 77,000 displaced from southern and eastern parts of the country.
Hezbollah and Israel have been engaged in cross-border warfare since the start of Israel's war on Gaza, which has killed more than 41,500 people, mostly women and children, following a cross-border attack by Hamas last Oct. 7.
The international community has warned against the strikes on Lebanon, as they raise the specter of turning the Gaza conflict into a regional war.