(CNN) -- A reporter was killed by a U.S. service member last July in southern Afghanistan in a case of mistaken identity, according to the results of an investigation by NATO's International Security Assistance Force.

Ahmad Omid Khpalwak -- a free-lancer for the BBC and Pajhwok News Agency in Afghanistan -- was killed during an insurgent attack in the Uruzgan province city of Tarin Kowt on July 28. He was 25 and joined the BBC in May 2008 as a stringer, the network said.

"Mr. Khpalwak was shot by an ISAF member who believed he was an insurgent that posed a threat and was about to detonate a suicide vest improvised explosive device," the NATO-led force said in a statement Thursday. ISAF identified the soldiers at the scene as Americans.

"The investigating officer found that the ISAF member involved in this incident complied with the laws of armed conflict and rules of engagement and acted reasonably under the circumstances."

Peter Horrocks, director BBC Global News, said the death is "a tragedy for his family and friends as well as his colleagues at the BBC."

It "further highlights the great dangers facing journalists who put their lives on the line to provide vital news from around the world," he said. "It is essential that journalists are given the best possible protection whilst reporting in dangerous situations so that the world can hear their stories."

Insurgents staged what ISAF said was a "complex attack" on a number of targets, including the provincial governor's compound and the Radio Television Afghanistan compound. The Committee to Protect Journalists said at least 22 people were killed and 37 people were injured.

Gen. John R. Allen, commander of ISAF, appointed an independent investigating officer to examine the circumstances of the death.

The report said two insurgents gained entry to the RTA compound when they used a car bomb to destroy a gate and a section of the wall.

From inside the building they traded fire with uniformed Afghan forces and shot at U.S. soldiers arriving at the scene. The firing from the insurgents eventually stopped amid escalating force by the Americans.

Afghan leadership told the forces that two suicide bombers were in the RTA building and that they "were not aware of any civilians present," ISAF said.