One Army sergeant was killed and two recruits were wounded Friday when a hand grenade exploded during a training session in this southern city, military officials said.

The accident took place at 11:13 a.m. at a drill camp of the South Korean Army in Daegu, North Gyeongsang Province, some 300 kilometers southeast of the capital city.

The explosion killed a 27-year-old instructor, Kim. He was rushed to a hospital but was later pronounced dead there at 12:53 p.m.

It also blew off the right hand of a 20-year-old recruit, surnamed Sohn, who was holding the grenade and injured 27-year-old recruit Park, who was waiting for his turn outside the trench, sources said.

The moment the military instructor ordered the trainee to "fling" his grenade, it went off, they added.

The military is investigating the exact cause of the explosion, including the possibility of defects or a mistake in handling the grenade. (Yonhap)