Prime Minister Fouad Siniora declared Saturday a national day of mourning in Lebanon, after a high-ranking police terror investigator and five other people were killed in a bomb blast in eastern Beirut. The attack expected to further deepen the already divided country.

Also, the Lebanon police said on Saturday the death toll in the attack rose to five from four and put the wounded at 42.

Friday's blast took place in the mainly Christian area of Hazmieh that houses many offices of major companies. Almost four cars were destroyed by the flames and the blast made a crater of 16 foot wide into the road.

An official funeral was held for Wissam Eid, who was posthumously promoted to Major, and his bodyguard at a police station just outside of Beirut. Eid was working for eight years for the ISF and was in his 30s.

A memorial service ceremony was held at ISF headquarters in Beirut before the funeral. "They thought that with their crime, they can affect our commitment and will, but they are really delusional," said Internal Security Forces chief Brigadier General Ashraf Rifi during the ceremony.

"We are determined to confront the empire of death and terror," he added.

The bodies of the captain and his bodyguard were taken to the northern city of Tripoli.

Mereb was buried in Tripoli while Eid was taken to his hometown at Deir Aamar, six kilometres farther north, where around 5,000 people gathered to bid him a last farewell.

"This is the third time that they tried to kill him. He was very kind, he had an important position, but to me he will always be a child," said Eid's mother for Reuters.

Lebanon has suffered so far at least 30 bombings in the last three years, mainly targeting anti-Syrian politicians and journalists. Police sources said at least five people were rounded up from the scene for questioning.

On Friday, Saad Hariri, the leader of Lebanon's Western-backed parliamentary majority and a scion of the Sunni Muslim community, implied that Syria could be involved in Eid’s murder. Eid was investigating the murder of former Prime Minister Rafiq Hariri, who died in a massive car bomb in February 2005.