Ahmad Nazar/AP Photo

Hundreds of American diplomats and aid workers in Kabul woke up Christmas morning to the sound of explosions, as the American embassy came under attack just after dawn.

The explosions sent staff at the embassy - who live on the same compound during their off-hours - scurrying to bomb shelters for cover.

The embassy sustained two hits from indirect fire, according to a US embassy statement provided to ABC. It's unclear if the "indirect fire" was mortars or rockets. The embassy is closed on Christmas day, and no Americans were injured. Embassy officials are now investigating the incident.

Rocket attacks aren't uncommon in Kabul, but direct hits on the US embassy are rare. It's unclear exactly where within the sprawling, heavily fortified compound the projectiles landed. Two rockets landed elsewhere in the city at around the same time, according to Afghan police.

The Taliban quickly claimed responsibility, saying they had targeted the embassy but made no mention of the Christmas holiday.

Unlike what the military calls "complex attacks," which typically involve weeks of planning and end with armed insurgents storming inside a building, rocket attacks like today's are difficult to prevent. Kabul is surrounded by mountains and hills, with several unoccupied, high rise buildings currently under construction, offering militants convenient vantage points to launch attacks unobstructed.

Despite how easy it is to launch rockets and mortars, their targeting is far from precise. Militants routinely launch mortars at coalition bases and other higher profile targets, but few ever hit their market, often landing outside the bases or in areas that are unpopulated. In a complex attack this summer, seven Taliban fighters occupied a vacant building under construction roughly two miles from a US military base near the Kabul airport. Despite the close proximity to the base, there were no casualties and all militants managed to do was launch a single rocket that tore a hole through an airplane hangar. In 2009, the Taliban launched a series of rocket attacks on Kabul during the country's elections. They claimed their target was the Presidential palace, but most landed outside the palace compound.