An Israeli bomb destroyed a UN observer post on the border, killing four peacekeepers on Tuesday, a UN official said.
The dead included observers from Austria, Canada, China and Finland, a senior Lebanese military official said, speaking on condition of anonymity because he was not authorized to release the information to the media.
The bomb made a direct hit on the building and shelter of the observer post in the town of Khiyam near the eastern end of the border with Israel, said Milos Struger, spokesman for the UN peacekeeping force in Lebanon known as UNIFIL.
"Rescue workers were trying to clear the rubble, but Israeli firing continued even during the rescue operation," Struger said. A UN official in New York said four people were killed. He spoke on condition of anonymity because the information had not been formally released.
US Ambassador John Bolton said the Security Council was informed that four officers with the UN mission -- known by its acronym UNIFIL -- were killed, but he had no other information. "We're obviously very sorry about that were attempting to get information where we can to confirm the nature of the incident," Bolton said.
In Rome, UN chief Kofi Annan was asked about the attack as he rushed out of a hotel following a dinner with US Secretary of State Condoleezza Rice and Lebanese Prime Minister Fuad Saniora. "I'm trying to get the details," he told reporters. Since Israel launched a massive military offensive against Lebanon and Hezbollah guerrillas from July 12, an international civilian employee working with UNIFIL and his wife have been killed in the crossfire between Israeli forces and Hezbollah guerrillas in the southern port city of Tyre.
Five UNIFIL soldiers and one military observer have also been wounded, Struger said.