Members of a Libyan militia have taken over an abandoned annex of the U.S. Embassy in Tripoli but have not broken into the main compound where the United States evacuated all of its staff last month, U.S. officials said on Sunday, according to The Associated Press.

A YouTube video showed the breach of the diplomatic facility by what was believed to be a militia group mostly from the northwestern city of Misrata, the AP reported.

Dozens of men, some armed, were seen gleefully crowded onto the patio of a swimming pool, with some diving in from the balcony of a nearby building, according to the AP.

Hassan Ali, a Dawn of Libya commander, said his fighters saw "small fires and a little damage" before they chased the rival Zintan militia out of the residential compound, the AP reported.

"We entered and put some of our fighters to secure this place and we preserved this place as much as we could," he said, according to the AP.

Libya has been rocked by the worst factional violence since the 2011 fall of Muammar Gaddafi, and a Misrata-led alliance, part of it which is Islamist-leaning, now controls the capital, the AP reported.

The United States withdrew all embassy personnel from Tripoli on July 26, driving diplomats across the border into Tunisia, amid escalating clashes between rival factions, and all sensitive materials were destroyed or removed from U.S. diplomatic sites in the capital before the evacuation. according to the AP.

The annex, apparently consisting of diplomatic residences and other facilities, lies about a mile from the embassy compound, the AP reported.

Security in Libya is an especially contentious subject for the United States because of the Sept. 11, 2012, attack on the U.S. mission in Benghazi, in which militants killed Ambassador Chris Stevens and three other Americans, according to the AP.