Afghan officials say a suicide car bomb attack has killed at least two people in Lashkar Gah, the capital of Afghanistan's volatile southern Helmand province.

The attack early Tuesday outside a police station also wounded at least three people. It was not immediately clear if the casualties were civilians or police officers.

Lashkar Gah was one of seven areas where control of security passed from foreign to Afghan forces in July as part of the first wave of a transitional process that is due to see all foreign combat forces leave Afghanistan by the end of 2014.

The attack comes one day after U.S. officials said an American citizen was killed and another wounded in a shooting incident inside the embassy's annex in Kabul.

A U.S. embassy spokesman said the incident took place Sunday night when an Afghan employee of the U.S. government opened fire on Americans before being killed himself.

The NATO-led coalition force said early Tuesday the shooting happened “inside the embassy compound,” and said it was “not an attack.”

The incident comes less than two weeks after militants launched a coordinated assault on several high-profile targets in the capital, including the U.S. embassy and NATO headquarters. Nine people were killed in a nearly day-long siege.