Correction: An earlier version of this article misidentified the son of Moammar Gaddafi who was killed in the NATO airstrike. Saif al-Arab Gaddafi was killed, not Saif al-Islam Gaddafi. This version has been corrected.

The U.S., British and Italian embassies were attacked and burnt by mobs in the Libyan capital Sunday, hours after a NATO airstrike was reported to have killed one of Moammar Gaddafi’s sons and three of his grandchildren.

Britain responded to the attack on its embassy and ambassador’s residence, which were gutted by fire, by expelling Libya’s ambassador to London. The United Nations announced that it had temporarily withdrawn its 12 international staff members from Tripoli and sent them to neighboring Tunisia after a mob entered its compound.

Libyan Deputy Foreign Minister Khaled Kaim said that only the commercial and consular department of the U.S. Embassy was attacked, but a former employee in Tripoli said the mob had caused extensive damage to buildings in the embassy compound and looted a warehouse.

A State Department spokesman said U.S. officials had “seen reports” of attacks on the U.S. Embassy but had no independent confirmation. A Tripoli resident, who asked not to be identified for his safety, said he had driven past the U.S. Embassy and seen black marks on the outside walls from fire, the green flag of the regime draped on the roof and pro-Gaddafi graffiti on the outside walls.

“If true, we condemn these attacks in the strongest possible terms,” spokesman Mark Toner said in Washington.

By not protecting foreign embassies, the Libyan government had “once again breached its international responsibilities and obligation,” he said.

Kaim said it was “a regrettable incident,” adding that mobs, some in the hundreds, attacked the lightly guarded embassies in the middle of the night. “That is why our police were outnumbered,” he said, adding that Libya promised to repair all the damage.

Meanwhile, in Moscow, Russia condemned the NATO airstrike Saturday on Tripoli, with the Foreign Ministry describing it as a disproportionate use of force.

Russia questioned NATO’s assertion that the alliance was not targeting Gaddafi or members of his family and called for “an immediate cease-fire and political settlement,” the Associated Press reported. Venezuelan President Hugo Chavez, an ally of Gaddafi’s, also condemned the strike.

The Libyan government said Gaddafi’s son Saif al-Arab Gaddafi, 29, was at a gathering of relatives and friends when three missiles struck the family house just after 8 p.m. Saturday, causing huge explosions. The Libyan leader and his wife, Safiyah, were at the house but escaped unharmed, government spokesman Moussa Ibrahim said, calling the attack an assassination attempt. Kaim said a 6-month-old granddaughter, a 2-year-old grandson and a 2-year-old granddaughter also died, as did a friend of Gaddafi’s son.

In Brussels on Sunday, NATO spokeswoman Carmen Romero said the reported deaths of Gaddafi’s relatives remained unconfirmed.

“We targeted a military command and control building with a precision strike,” Romero told the AP. “It was not targeted against any individual. It was a military target, clearly linked to the Gaddafi’s regime’s systematic attacks on the civilian population.”

The White House on Sunday referred all questions about Saturday’s airstrike to NATO headquarters. But a White House official said the president does not review target lists in advance.

Prime Minister David Cameron of Britain, which has been at the forefront of the NATO campaign, told the BBC that the strike was in line with the U.N. mandate to prevent “a loss of civilian life by targeting Gaddafi's war-making machine.”

Sen. John McCain (R-Ariz.), who recently returned from Libya, told CBS News’s “Face the Nation” that it is “not as easy as you think” to eliminate dictators or terrorist chiefs. “So we should be taking out his command and control, and if he is killed or injured because of that, that’s fine.”

Rebel-held city shelled

NATO has been accused of not doing enough to protect Libya’s citizens and responded by stepping up attacks on what it says are Gaddafi’s command and control centers, particularly in Tripoli.

But in Misurata, NATO has failed to prevent the heavy shelling of the besieged rebel-held city and its port. On Sunday, Libyan government forces unleashed a fresh barrage of shells on the port, as a humanitarian ship was unloading. Eight people were killed in the city Sunday and 23 were wounded, rebel spokesman Mohamed Ali said via Skype.

The Libyan government had tried to lay anti-ship mines in Misurata harbor Friday and threatened to attack any ships entering the port, including those carrying humanitarian aid, because rebels also are using the port to bring in arms, ammunition and weapons.

Emotions rose in Tripoli after the death of Gaddafi’s son was announced.

Video taken on a mobile phone by the Tripoli resident showed a car destroyed by fire, windows smashed and huge fire marks on the outside walls of the British ambassador’s residence. He said two police officers armed with Kalashnikovs at the gate had made no attempt to stop young men and children from entering and exploring the building.

British Foreign Secretary William Hague condemned the attacks and said that as a result of Libya’s failure to protect the missions, he had “taken the decision to expel the Libyan ambassador,” noting that the official, Omar Jelban, had 24 hours to leave Britain. “The attacks against diplomatic missions will not weaken our resolve to protect the civilian population in Libya,” he said.

The Italian Foreign Ministry said in a statement that “there were attacks of vandalism against the buildings of a number of foreign embassies in Tripoli, including the Italian Embassy.”

Britain, Italy and the United States had withdrawn diplomatic staff from Libya weeks ago. In March, Britain also expelled five Libyan diplomats in protest of the Libyan regime’s actions, saying they could pose a threat to national security.

Clear signs of residence

Reporters were taken to the destroyed residence before dawn Sunday and again in daylight hours. There were no obvious signs of military command and control facilities, but there were clear signs that the buildings were being used as a residence at the time of the attack.

In a kitchen, rice, pasta, fish and stuffed peppers were on a stove, with a wall clock stopped at 8:08 p.m., the time of the attack. In the building, which took a direct hit, women’s dresses were buried in the concrete debris and dust, while a mounted elephant’s tusk was visible.

Ibrahim, the Libyan government spokesman, said intelligence about Gaddafi’s whereabouts or plans must have been leaked to NATO, he speculated. “Is it satellite technology? Is it some listening devices?”

Onlookers traipsed through the ruins, and a busload of women brandishing portraits of Gaddafi arrived to chant slogans, shouting that foreign journalists were “liars.” Outside, a car slowed down and its passengers shouted that the foreign media were “dogs.” Gaddafi’s regime says the foreign news media have not reported the truth about the support he enjoys among ordinary Libyans, and government minders openly tell reporters that they are to blame for NATO airstrikes and the deaths of Libyan children.

Then another car drove up, dragging a large American flag from its bumper. After a brief attempt to burn the flag, the crowd, chanting pro-Gaddafi slogans, tore it to shreds.

Although people in opposition-held eastern Libya were skeptical about news of the death of Gaddafi’s son, suspecting the Libyan leader was playing a trick to undermine NATO’s resolve, a French surgeon said he had examined the bodies of one man and two of the dead children.

“According to the photos we have seen, it is very probably the son of Colonel Gaddafi,” said Gerard Le Clouerec of the Rhama Clinic, adding that the skin on man’s face was largely intact but that his skull was in pieces from the pressure of the blast. “I can’t be absolutely certain, but it is the same type of young man, the same size, the same beard and thin moustache.”

Staff writers Scott Wilson and Joby Warrick in Washington and Leila Fadel in Benghazi contributed to this report.