An Afghan soldier what shot dead Sunday after opening fire inside a base in the southern Helmand province and wounding three U.S. soldiers.
Navy Cpt. Bill Salvin, a spokesman for the U.S. military, said coalition forces killed the Afghan soldier "to end the attack."
A spokesman for the Afghan army, Col. Mohammad Rasoul Zazai, said the soldier made a "mistake" and had not opened fire deliberately.
In recent years, several U.S. servicemembers have been killed in Afghanistan as part of so-called insider attacks that have been carried out by Afghan police or soldiers.
An American soldier and civilian contractor were shot and killed last October inside a military base in Kabul. The Afghan man accused of killing them was wearing a military uniform at the time of the attack.
In addition, The Guardian reports that two Romanian soldiers were killed last year by members of the local Afghan police unit they were training.
Elsewhere in Afghanistan
Taliban insurgents carried out a suicide bombing at a district headquarters in the Kandahar province, Samim Khpolwak told the Associated Press. It is still unclear how many people were killed or injured in that attack.
An unnamed security official said six police officers and five others were killed in the Taliban-claimed attack.
The Associated Press contributed to this report.