Opposition figures in Lebanon have accused Syrian and government authorities of being responsible for the death of former Prime Minister Rafik al-Hariri.
Mr al-Hariri was killed when a massive car bomb exploded in the Lebanese capital, Beirut, today.
12 other people, including some of Mr al-Hariri's bodyguards, were also killed. Around 100 others were injured.
Mr al-Hariri was on his way back from parliament when his motorcade was attacked.
A self-made billionaire businessman, he had been the leading Lebanese politician since the end of the civil war in 1990, and prime minister for most of the last 15 years.
He resigned in October amid differences with Lebanon's pro-Syrian President, Emile Lahoud.
In a statement after an emergency meeting in Beirut, the opposition called on the government to resign and also called for Syrian forces to pull out before elections in May.
Tonight Lebanon's army said it had gone on alert, deploying patrols and setting up checkpoints.
Lebanese security forces have also raided the Beirut home of a man they identified as a Palestinian who appeared in a video claiming responsibility for the killing of Mr al-Hariri.
A Lebanese security source said Ahmed Aboul Adef was not in the house at the time of the raid.
Killing widely condemned
The White House denounced the killing of Mr al-Hariri, and said that the Lebanese people must be able to build a future 'free from Syrian occupation'.
French President Jacques Chirac has called for an international inquiry to determine who was responsible for Mr al-Hariri’s assassination.
Pakistani President Pervez Musharraf condemned the killing as a 'terrorist' attack, while Saudi Arabia said the attack was 'evil'.