The US ambassador to Libya, Christopher Stevens, along with three other embassy staff, were killed Tuesday night following an attack on the US consulate in Benghazi, US President Barack Obama confirmed Wednesday afternoon.

At least five Americans and 10 members of the Libyan security forces were wounded as mobs, allegedly protesting against an anti-Islam film, stormed the US mission armed with rocket propelled-grenades. 

The cause of the deaths has yet to be revealed. However, a senior US official told CNN Wednesday that the diplomats died of smoke inhalation while trying to escape to the roof of the burning building after it was blasted by a grenade. 

The official added that several "valiant but unsuccessful" attempts were made to get back into the consulate and rescue Stevens  and the others, who had been separated from the rest of their team. 

US President Barack Obama issued a statement, Wednesday morning, "strongly" condemning the "outrageous" killing of four Americans and paying tribute to Stevens and his slain colleagues.

At a later press conference at the White House, the US president commented that "it is especially sad that Stevens died in Benghazi, as it is a city that he helped to save," making reference to the US ambassador's previous roll as envoy to Libya's National Transitional Council.  

Obama added that Tuesday night's events would "not break the bonds between the US and Libya."

US Forces deployed to Libya

The US president announced that America was stepping up security at their diplomatic posts worldwide. In addition, America ordered some 50 US Marines part of Fleet Antiterrorism Security Team, or Fast, to Libya in order to bolster security.

Wednesday evening, a senior US official told CNN that unmanned surveillance drones were expected to begin combing the Benghazi area for "jihadi encampments and targets" involved in Tuesday's attack. The FBI will also launch their own investigation, security sources said, and the Pentagon and other US agencies will review video footage. 

US Secretary of State Hillary Clinton revealed the name of the second victim, father-of-two Sean Smith, a State Department information management officer who had served in Baghdad, Pretoria, Montreal and The Hague, in the afternoon. 

The identities of the two other officials, who are thought to be US marines, are being withheld while colleagues attempt to contact their families.

Speaking at the State Department in her second statement of the day, Clinton described those behind the attacks as a "small and savage group, not the people or the government of Libya." She added that Libyans fought to defend the US post and carried Stevens' body to hospital as well as helping other Americans to safety. 

The secretary of state went on to say that there was "no justification for this" and that it was "especially difficult" that the event took place on the anniversary of 11 September 2001 attacks on America. 

The ambassador had, according to Al-Jazeera journalist Suleiman Idrissi in Benghazi, been paying a short visit to the Eastern Libyan city, when the US building came under attack. The bodies of the dead, the pan-Arab news agency reported, were transported to the Benghazi international airport, to be flown to Tripoli and then onwards to a major US airbase in Germany.

Libyan embassy guards "lacked" weapons

In a Wednesday afternoon press conference, Libyan Deputy Interior Minister Wanis Al-Sharif admitted that the Libyan Interior Ministry "lacks necessary equipment and weaponry."

He defended the Libyan security forces guarding the embassy who were overwhelmed by the attackers, saying: "If the premises are attacked by a large number of heavily armed people, it is almost suicidal... It was imperative to withdraw the guards."

The deputy interior minister also confirmed that the Libyan authorities have launched investigations into the incident but that "it is very difficult as the number of protesters exceeds hundreds." Al-Sharif claimed "remnants of the former [Gaddafi] regime" were responsible.

Investigations underway

Following the deputy interior minister's statements, Libyan President Mohamed Al-Megarif apologised to the US "its people and the whole world" for the attacks, during a joint press conference with Libyan Prime Minister Abdurrahim Al-Keib.

"We condemn, reject and denounce what happened in Benghazi yesterday," Al-Megarif said, "we totally reject that our home soil be used as a stage for an act of revenge."

Neither the president nor the prime minister would disclose any details of the event insisting that all will be revealed when the investigation is complete.

Libya's leaders also announced that a joint committee has been established to follow up on security measures and to ensure that the perpetrators are punished. 

British Foreign Secretary William Hague, who was in Cairo Tuesday on an official visit to Egypt, also condemned the attack in­­ a statement Wednesday.

"There is no justification for such an attack and the appalling death of an US official," Hague said, pledging British support to the Libyan authorities.

Hague urged the Libya to take "urgent action to improve security" and to find those responsible.

Targeted attack?

The armed mobs that attacked Benghazi's US consulate and set fire to the building on Tuesday were, reportedly, protesting against a film ridiculing the Prophet Mohamed. The American-Israeli director of the 13-minute video entitled "Innocence of Muslims" has since gone into hiding. 

However, some doubt has been cast over the motives of the gunmen. US sources told CNN, Wednesday, that the assault was planned in advance and the attackers used the protest outside the consulate as a diversion.

It is not clear if the attackers instigated the demonstration or simply took advantage of the situation, the source continued, however they did not believe that Stevens was specifically targeted.

Growing violence towards diplomatic community

Tuesday night's events come after several attacks on consulates in Benghazi over the course of the last few months. 

On 21 August, an Egyptian diplomat in Benghazi was targeted by a homemade car bomb. On 18 June, a group of armed gunmen stormed the Tunisian consulate. A week earlier, a British embassy convoy, which included the Ambassador Dominic Asquith, was attacked by a rocket-propelled grenade.  

Following Tuesday's attacks, the United Nations Security Council issued a statement, reminding the Libyan government of the "inviolability of diplomatic and consular premises" and the "obligations on host governments" to protect the buildings.

For their part, Human Rights Watch, Wednesday evening, said the killing of the US embassy personnel was "wake-up call to the Libyan government on the need to rein in armed groups that have been defying the law in Libya."

Stevens, 52, had served in the American foreign office for 21 years and was envoy to Libya's National Transitional Council during the Libyan uprising last year. The last US ambassador to be killed on duty was Adolph Dubs who died in an exchange of fire during a kidnapping attempt in Afghanistan in 1979.

Protests occurred on the same day in Cairo, where thousands gathered at the US embassy and took down the American flag to condemn the anti-Islam film.