An Afghan employee has killed one US citizen and wounded another before being shot dead at a compound believed to house a CIA station, officials say.

The incident in Kabul took place on Sunday night at the facility, previously known as the Ariana hotel.

It comes two weeks after militants attacked the US embassy and government buildings in Kabul, leaving 25 dead.

The motives for the shooting are as yet unclear. Afghan CIA employees usually undergo rigorous security screening.

The BBC's Paul Wood in Kabul says that it is unclear if the gunman was a Taliban recruit or if the shooting happened as a result of a personal dispute which escalated into serious bloodshed because of the presence of weapons.

According to one source, when the gunman opened fire he was shooting in all directions, our correspondent reports.

Afghan counter-intelligence sources told the BBC that their personnel in the area heard an explosion and gunfire which lasted nearly 10 minutes.

The compound is located in the most secure part of Kabul - near the US embassy and Nato military bases.

Meanwhile, a source in the nearby Afghan presidential palace told the BBC: "After the explosion was heard, an Afghan National Army (ANA) vehicle was passing. CIA-employed guards opened fire on the vehicle, thinking it had attacked them."

The sources said that two ANA soldiers, one CIA guard and one presidential guard were injured.

Earlier this week, Burhanuddin Rabbani, the chief of Afghanistan's High Peace Council, was killed in a suicide bomb attack in the Afghan capital.