A powerful explosion in the Hezbollah militant group's Beirut stronghold killed four and wounded at least nine, according to the Red Cross. More casualties are expected given the density of the area.
The explosion was caused by a car bomb planted in an SUV, according to NBC News' Mustafa Kassem. There are also reports that the attack occured near Hezbollah's political headquarters.
The Lebanese capital has been hit by a series of attacks in recent months. The civil war in neighboring Syria has spilled into the small country, polarizng Lebanon and ratcheting up dormant sectarian tensions.