KABUL: At least eight members of the security forces were killed by two of their colleagues in southern Zabul province late Friday night, An Afghan official said.

Gul Islam Seyal, spokesman for the provincial governor, said Saturday that both attackers fled the area after killing their colleagues in Shinkia district.

He said the two policemen also took all the weapons and ammunition from the checkpoint.

Seyal said an investigation is underway to find out what caused the incident or if the two have links to insurgent groups.

Insider attacks are not unusual in Afghanistan. In a similar incident in late February, 11 police were shot and killed by another policeman from the same checkpoint in neighboring Helmand province and the attacker managed to flee in a police vehicle.

Separately on Saturday, in eastern Khost province a possible suicide bomber was shot and killed by security guards near the entrance to an airport, said Gen. Faizullah Ghyrat, provincial police chief in Khost.

"There were three suspects who wanted to get closer to the eastern gate of the airport, one was killed by the guards and two others disappeared after the first one was killed," said Ghyrat.

No group has claimed responsibility for the attack in Khost.