"Suicide bomber blows himself up in a car... In Haret Hreik, two people killed and five injured," Lebanon's National News Agency said.
"Body parts apparently belonging to a suicide bomber were at the scene," it added.
The attack took place on a busy commercial street that was targeted by a suicide car bombing in early January.
"The explosion took place on Al-Arid street in Haret Hreik," Hezbollah's Al-Manar news station reported.
Al-Manar broadcast images of firemen working to put out a massive blaze, as scores of people gathered at the scene of the blast.