No one was hurt but local residents said it shows the danger to their lives from the US facilities in Pocheon, Gyeonggi Province.

The US Eighth Army, the core unit of the US Forces Korea, announced that a combined investigation with South Korean and US experts has been completed.

It said its commander Lt. Gen. Thomas S. Vandal met with senior South Korean defense ministry officials and lawmakers to "discuss the findings of the investigation and the resumption of firing at Rodriguez range."

It did not elaborate on the outcome of the probe in a brief statement.

"We regret that this incident occurred, and the Eighth Army is committed to conducting safe operations at all times," said Vandal.

"The training we conduct at Rodriguez range is crucial to keeping the Alliance ready to fight tonight, and the safety of our service members, civilians and the community will always remain our top priority."

American troops resumed ground firing on Tuesday, while aerial gunneries are expected to resume next month. (Yonhap)