Beirut has been hit by a huge explosion, apparently targeting a stronghold of the Shi'ite Hezbollah militant group.
The blast, in Beir el-Abed, a suburb in the south of the capital, was reportedly caused by a car bomb left in a shopping centre, near offices of Hezbollah officials.
Security sources said at least 53 people had been wounded, though reportedly none seriously and there were no fatalities.
Hezbollah's Al-Manar TV station broadcast footage of a thick plume of smoke rising into the sky at the site of the blast as people rushed to take casualties to the hospital.
Images from the scene showed a crater covered by a blue tarpaulin and surrounded by wrecked cars. Hezbollah representatives with red caps and yellow armbands set up a security cordon around the blast scene along with Lebanese soldiers.
Gunmen from the organisation were seen arresting two men near the scene.
Shopping areas have been extremely crowded as it is the day before the Islamic holy month of Ramadan begins. A large fire is reportedly burning at the blast site, which was near a petrol station.
"This is the work of agents trying to create strife in Lebanon," Hezbollah parliamentary deputy Ali Meqdad said at the site of the explosion.
The interior minister, Marwan Charbel said the attack was "a criminal act aimed at destabilising the country and creating Sunni-Shi'ite sectarian strife". President Michel Suleiman said it reopened the "black pages" of Lebanon's civil war.
Some Syrian rebel groups have threatened to strike in Lebanon after Hezbollah joined the side of Syrian president Bashar Assad in the Syrian civil war.
In May, two rockets hit a Hezbollah stronghold in south Beirut, wounding four people. The rockets struck hours after Hezbollah leader Sheikh Hassan Nasrallah vowed to help Assad to victory.
Hezbollah's fighters were instrumental in a recent regime victory when government forces regained control of the strategic town of Qusair near the Lebanese border.
Abu Ali, who lives near the scene of the explosion, blamed what he called Sunni terrorists for the attack.
"They want to terrorise us. The scumbags. These terrorists want us to abandon (the leader of Hezbollah) but we swear we will love him more, for all our lives. All we own, and our children we pledge to him."