BEIRUT, Lebanon (CNN) -- An Israeli airstrike hit a United Nations post in the southern Lebanon late Tuesday, killing four of the agency's observers, according to the U.N. Interim Force in Lebanon.

UNIFIL sent a rescue-and-medical team to the city of Khiyam, and the team was trying to clear rubble early Wednesday. UNIFIL said there were at least 14 incidents of firing close to the post since Tuesday afternoon.

The Israel Defense Forces said it was looking into the report, which came as U.S. Secretary of State Condoleezza Rice proposed an ambitious plan in which international military forces would help the Lebanese government stabilize southern Lebanon, Lebanese political sources said.

And this just broken by CNN and confirmed here by The Australian:

UN attack looks deliberate: Annan
From correspondents in Rome
26jul06

UN Secretary General Kofi Annan today said he was "shocked" at Israel's "apparently deliberate targeting" of a UN post in Lebanon, in which up to four UN observers were killed.

Mr Annan described the strike as a "co-ordinated artillery and aerial attack on a long established and clearly marked UN post." He said it took place "despite personal assurances given to me by Prime Minister Ehud Olmert that UN positions would be spared Israeli fire."

"Furthermore, General Alain Pelligrini, the UN Force Commander in south Lebanon, had been in repeated contact with Israeli officers throughout the day on Tuesday, stressing the need to protect that particular UN position from attack.

"I call on the Government of Israel to conduct a full investigation into this very disturbing incident and demand that any further attack on UN positions and personnel must stop.

"The names and nationalities of those killed are being withheld pending notification of their families. I extend sincere condolences to the families of our fallen peacekeepers."

I think it's pretty safe to say that any hope for diplomacy has gone completely out the window. Why would Israel deliberately target UN observers? Does it have to do with reports of white phosphorous being used by the IDF? Daniel Ayalon, Israeli Ambassdor to the US calls for Annan to apologize for his"shocking" and "deplorable accusations", and accuses Annan of "jumping to conclusions". He also alluded that Hezbollah may have actually been responsible for the attack on the UN observers.