SEOUL - Five South Korean soldiers were killed and seven others wounded at a shooting spree accident that occurred in a frontline Army unit at the inter-Korean land border, local media reported Sunday.

A South Korean Army sergeant, who was serving sentry at the Demilitarized Zone, fired around 10 random shots with his K-2 rifle against fellow South Korean soldiers at about 8:15 pm Saturday, according to military officials.

At the time, the sergeant, identified only by his surname Lim, had 75 live ammunitions and a hand grenade.

The firing rampage took place at a general outpost of the 22nd Infantry Division in Goseong, a northeastern town in Gangwon Province bordering the Democratic People's Republic of Korea (DPRK) .

A sound of explosion was heard near the scene of the rampage, but it is yet to be determined whether the sergeant threw his grenade.

Lim, who was on the list of soldiers to require more attention than others, fired shots at fellow servicemen right after returning to the barrack near the post following his guard duty for some six hours from 2 pm.

Five soldiers were killed, with seven others injured. The casualties included a staff sergeant, a sergeant, a corporal and two first-class privates. The injured included two staff sergeants, two sergeants, two first-class privates and a private.

Among the seven wounded, two sustained serious injury. The two soldiers, whose legs the bullet penetrated, were taken to nearby military hospitals by helicopter, and the remaining five were admitted to private hospitals.

It would be the deadliest military accident since June 2005 when a South Korean Army soldier threw a grenade in the barrack and opened random fire at fellow soldiers, killing eight and wounding two.

The military and police were pursuing the killer who is at large with his K-2 rifle and tens of live bullets.

The military issued the Jindoggae 1, the highest defense readiness to counter possible infiltration or provocation from the DPRK, to search for the fugitive soldier. The police stepped up checks and inspections near the town.

Sentries of the 22nd Infantry Division strengthened vigilance to block the possibility for the sergeant crossing into the DPRK.

The Defense Ministry launched an emergency management team to deal with the incident, and the Army sent an inspection team to the scene to figure out the causes.