BEIRUT — An explosion ripped through a Hezbollah militant stronghold in a southern suburb of Beirut Thursday, killing or wounding at least 120 people, Lebanon’s official National News Agency said.

The Lebanese army released a statement saying it was a car bomb. The blast hit a main road separating the Ruweis and Bir El Abed areas, which are usually crowded in the early evening.

Homes, shops and cars parked on both sides of the road were damaged and New TV said six buildings were on fire.

Flames were seen spreading across the street in televised footage and thick black smoke covered the site as ambulances and civil defense personnel rushed to the scene. Firefighters were evacuating residents in nearby buildings. LBC TV reported several dead and injured removed from the buildings.

The blast occurred a day before a planned Hezbollah rally in south Lebanon to mark the end of a month-long war the group fought with Israel in 2006. Hezbollah chief Hassan Nasrallah is scheduled to address the rally via video link.

Hezbollah has sent fighters to help the government of Syrian President Bashar al-Assad crush an insurgency that began in March 2011. The rebels have said they would strike Hezbollah inside and outside Lebanon.

A group calling itself the Brigades of Aisha Umm al- Moemeneen claimed responsibility for the blast in a YouTube video, which couldn’t be authenticated. It showed two men with guns flanking a third man seated as he made the claim.

All three wore white masks. The man addressed Hezbollah chief Hassan Nasrallah, saying it was the second time the group had targeted the suburb, and that there will be more attacks.

Hezbollah lawmaker Ali Ammar told Al Manar the blast was a “big terrorist crime.”

A bomb placed inside a parked car in Bir El Abed last month wounded 53 people.