A car burns at the site of an explosion in east Beirut
A senior Lebanese intelligence official was among at least eight people killed in a massive car bomb attack in central Beirut, state media say.
Wissam al-Hassan was said to be close to opposition leader Saad Hariri, a leading critic of the government in neighbouring Syria.
No group has claimed Friday's attack, which was condemned by Damascus. Dozens of people were injured, reports the BBC.
Tensions in Lebanon have been rising as a result of the Syrian conflict.
Lebanon's religious communities are divided between those who support the government of Syrian President Bashar-al Assad - notably the Shia - and those, such as many Sunnis, who back the rebels.
Friday's attack was the deadliest in Beirut since 2008.
It occurred in the mainly Christian district of Ashrafiya, in a busy street close to the headquarters of the Hariri's 14 March coalition.
Saad Hariri is the son of ex-PM Rafik Hariri, a Sunni who was assassinated in a 2005 bomb attack which many Lebanese blamed on Syria.
Some 14 March politicians have accused the Syrian government of being behind the bombing.
However Syrian Information Minister Omran al-Zoubi called it a "cowardly terrorist act".
Lebanese Prime Minister Najib Mikati said the government was trying to identify the perpetrators and said they would be punished.
The blast, which was heard several kilometres away, set many cars ablaze and destroyed the facades of nearby buildings.
Ronnie Chatah, who lives nearby, told the BBC: "The building shook and it echoed throughout the neighbourhood."
Hospitals across the city have reported large numbers of wounded, and called for people to donate blood.
Reports say Sunni Muslims took to the streets and burned tyres in many parts of Lebanon in protest against the attack.