US Ambassador to Libya Christopher Stevens, along with three members of his staff, was killed Tuesday night during an attack on the US consulate in Benghazi, Libya sparking condemnation by the international community.
While the exact cause of the deaths has yet to be confirmed, a senior US official told CNN Wednesday that the fleeing diplomats had died of smoke inhalation while trying to escape to the roof of the burning building after it was struck by a rocket-propelled grenade.
The official added that several "valiant but unsuccessful" attempts had been made to rescue Stevens and his colleagues – who had been separated from the rest of their staff – from the building.
Meanwhile, doubts have been cast over the attackers' motives, with US sources telling CNN that the assault had been planned in advance and that the attackers had used a demonstration outside the consulate as a diversion.
It remains unclear whether the attackers instigated the demonstration – held to protest a film seen as defamatory to Islam – or simply took advantage of it. The sources, however, said they did not believe that Stevens had been specifically targeted.
In response to the incident, US President Barack Obama on Wednesday announced that the US was stepping up security at diplomatic posts worldwide.
In addition, Washington ordered an anti-terrorism Marine fleet to Libya with the stated aim of bolstering security. The Fleet Antiterrorism Security Team (FAST) assigned to Libya is thought to consist of some 50 marines.
On Wednesday evening, a senior US official told CNN that unmanned surveillance drones were expected to begin combing the region around Benghazi for "jihadi encampments and targets" involved in Tuesday's attack.
Tuesday's deadly attacks followed similar protests outside the US embassy in Cairo, where thousands of demonstrators converged to protest against the controversial film.
Stevens is the first US ambassador to be killed on duty since 1979, when Ambassador Adolph Dubs died during a botched kidnapping attempt in Afghanistan.