Security forces are hunting the lone gunman who they suspect of shooting dead the commander of the mountain post near the country's border with Kazakhstan, said Gulmira Borubayeva, a spokeswoman for the border guard service.
Three other soldiers and the wife of a serviceman were also killed in the attack, but three other border guards managed to escape after hearing the shooting, she said.
It was not immediately clear why the accused border guard would have embarked upon such a killing spree.
The border guard service is a division of the State Committee for National Security, successor to the Soviet-era KGB. Reinforcements have been sent to hunt the fugitive suspect, the border guard service said in a statement.
The assault follows the killing in late May of 14 Kazakh border guards and a herder at a remote post near Kazakhstan's frontier with China. The victims were shot and the border post set on fire.
The single surviving border guard admitted to the killings, though later withdrew his confession. Kazakh prosecutors said at the time that hazing, or severe military bullying, could have prompted that massacre.