BEIRUT -- A car bomb damaged a US diplomatic car in Beirut on Tuesday, killing at least three people and wounding 16, and the US State Department said no Americans died in the blast.

The bomb sent a column of smoke into the sky, tore masonry from buildings and destroyed at least six cars in a Christian suburb north of Beirut, as well as damaging the armored embassy car.

The blast coincided with US President George W. Bush's visit to Saudi Arabia as part of a weeklong tour of US Middle East allies.

Bush is not visiting Lebanon, though Washington has been a strong backer of the Beirut government in its power struggle with the Hezbollah-led opposition backed by Syria.

The Lebanese government put the death toll at three but the State Department said the bomb killed four Beirut residents. None worked for the embassy.

"There were no American diplomats or American citizens in the car at the time," State Department spokesman Sean McCormack said. A Lebanese national working for the US Embassy and a driver were in the car when it was attacked, and the driver was slightly wounded, he said. An American passer-by was also hurt.

Lebanese and US security officials were at the scene, where rescue workers covered a corpse with plastic sheeting. Pools of blood covered the road. Two of the dead were Lebanese and the third a Syrian, security sources said.

"I'd like ... to just state the outrage of the United States against the terrorist attack that took place in Lebanon today," US Secretary of State Condoleezza Rice, who is traveling with Bush, said in Riyadh.

"To the degree that there is any thought of intimidation in an attack of this kind, the United States will of course not be deterred in its efforts to help the Lebanese people, to help the democratic forces in Lebanon, to help Lebanon resist foreign interference in their affairs," she said.

U.N. Secretary-General Ban Ki-moon "deplores this act of terror and extends his sympathies to the families of those killed and injured," spokeswoman Michel Montas said in a statement.

Lebanon has seen more than 30 explosions in the past three years, many hitting anti-Syrian politicians and journalists.

Members of the US-backed governing coalition who have blamed Damascus for previous attacks condemned the bombing but did not name any suspects.

POLITICAL, SECURITY WOES

Lebanon's stability has also been rocked by attacks on U.N. peacekeepers in the south and an insurrection by al Qaeda-inspired Islamist militants in the north last year.

Alongside its security problems, the country has been suffering a political conflict pitting the governing coalition against the Hezbollah-led opposition.

The government said in a statement the best response to the attack should be commitment to an Arab initiative to end the political crisis. Arab League Secretary-General Amr Moussa is due in Beirut Wednesday to resume a mediation effort.

The dispute has paralyzed government for more than a year and blocked the election of a new president, leaving Lebanon with no head of state for the first time since its 1975-90 civil war.

US personnel in Lebanon were targeted during that conflict by Iranian-backed groups, including militants who blew up the US Embassy in 1983 and kidnapped American diplomats.

Hezbollah, which is backed by Iran and listed by Washington as a terrorist group, had described Bush's tour as a "black day" for the region. Sayyed Hassan Nasrallah, the group's leader, denounced the bombing "regardless of who might be targeted."

US Ambassador Jeffrey Feltman is due to leave his post at the end of January and the embassy cancelled a farewell reception marking his departure later in the day.