A security source told Naharnet that the blast took place at the entrance to a three-storey building in Kfarkila, adding that it is believed to be the result of a bomb.
The source identified one of the tenants in the building as Mohammed Zreiq, who is believed to be a Hezbollah official.
He said two of Zreiq's children, aged 7 and 11, were among the wounded. The third casualty was identified as a 15-year-old student.
However, the country's state-run National News Agency (NNA) reported that the local residents said the father is just an ordinary person doing business in Africa.
The NNA said that Lebanese troops and police officers later cordoned off the building and an investigation was under way.
Kfarkila has long been a stronghold of Hezbollah, which fought a devastating 34-day war with Israel in 2006.