SEOUL, South Korea (AP) — A South Korean reserve soldier went on a shooting spree during a mandatory training session in Seoul today, killing a fellow reservist and injuring three others before killing himself, officials said.

The 24-year-old soldier, surnamed Choe, abruptly turned around and fired seven rounds with a K-2 rifle on fellow reservists after firing one round during shooting training, army and defense officials said on condition of anonymity because of office rules. He was initially given 10 bullets and used the ninth bullet to committee suicide after the rampage, they said.

It was not immediately known why Choe opened fire. But Yonhap news agency, citing the army, reported that Choe was put within a group of soldiers who needed special attention when he was on active service and that he received medical treatment for depression. The Defense Ministry and the army couldn’t immediately confirm the report.