KABUL – A gunman in an Afghan army uniform on Wednesday shot dead at least two American advisers and wounded three more near a base in the Afghan capital before being killed himself, officials said.

The American deaths included one soldier and one civilian, while one soldier and two civilians were injured and in stable condition, the U.S. military command in Kabul said in a statement.

"The two individuals were killed during an attack near a coalition base by an unknown assailant, who was later killed," the statement said. "They were conducting duties as part of the larger NATO mission to train, advise, and assist the Afghan security services."

About 13,000 international troops and thousands of additional civilian contractors remain in Afghanistan to train and assist government forces battling Taliban insurgents hoping to reimpose a fundamentalist Islamic regime 15 years after they lost power in a U.S.-led military operation.

The shooting took place at about 11 a.m., while the international troops were visiting a base in Kabul, said Dawlat Waziri, a Defence Ministry spokesman.

He said reports indicated the suspected attacker, who was killed when the international troops returned fire, was wearing an Afghan army uniform.

American officials said they were investigating the incident.