Hezbollah confirmed earlier on Wednesday that Shukr was in a building hit by Israel but could not comment on his fate at the time.
"The body of Hezbollah commander Fuad Shukr has been found under the rubble of a building in the southern suburb of Beirut," the source said.
On Tuesday, the Israel Defense Forces (IDF) announced that it had carried out a strike in the southern suburb of Beirut, targeting a "commander responsible for the murder of the children in Majdal Shams and the killing of numerous additional Israeli civilians." Later, the IDF said that the "most senior military commander" of Hezbollah, Fuad Shukr, had been killed in the strike.
Lebanese media reported that at least four people had been killed and 74 others had been wounded in the attack.
According to Arab media, Shukr was the chief military adviser to Hezbollah Secretary General Hassan Nasrallah.