The Shiite terror group announced that three of its members were killed and a few others were injured in the blasts, which hit an arms stockpile in a building under construction in an uninhabited area between the villages of Nabishit and Khodr.
"Sources from the resistance (Hezbollah) reported that a blast took place in an arms depot of shells, ammunition and remnants of Israel's shelling in the area," said Hezbollah.
"This unfortunate blast led to the martyrdom of three fighters," the Lebanese terror group said in a statement carried by its television channel, Al-Manar.
"Work is continuing in order to deal with the accident, in coordination with the relevant agencies," the Hezbollah statement added.
Among the wounded were four Syrian workers, the security official added.
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Residents said the building collapsed as a result of the blasts. Dozens of ambulances arrived at the scene as members of Hezbollah surrounded the area, the residents told AFP.
Meanwhile, Lebanon’s National News Agency reported that three explosions were heard in the Lebanese mountainous area between the Baalbek towns of Al-Nabi Sheet and Al-Kharybeh.
It also said that a house belonging to a man named Mohammad Ali Rida al-Moussawi "was completely destroyed" by the explosion and that a number of residents in the surrounding area were injured and admitted into hospitals in the Baalbek region.
Hezbollah MP Kamel Rifai told The Daily Star that his group does not store arms in towns. "The area where the reported blast took place is an industrial and agricultural area, so it could have been anything," said the MP.
Rifai told the Lebanese newspaper that he had earlier toured near the region and that nothing was amiss in the area. "Civil and social centers run by Hezbollah were not on alert and everything was operating smoothly," the MP said.
Hezbollah, which fought a devastating 2006 war with Israel, has a huge arsenal of tens of thousands of rockets, which it says it needs to retain in case of any new conflict with the Jewish state.
Hezbollah and its allies, which lead Lebanon's governing coalition, support Syrian President Bashar Assad in his 18-month battle against rebels seeking to oust him. The Lebanese opposition is bitterly opposed to the Damascus regime.