Separate attacks in northern Afghanistan on Tuesday, September 22, killed at least 15 Afghan troops, including 10 soldiers who died in an "insider attack" when a fellow soldier smuggled insurgents inside a checkpoint to kill his colleagues, officials said, according to the Associated Press.

No group immediately claimed responsibility for the assaults. The so-called insider attacks — incidents when an Afghan soldier or policeman turns his gun on fellow troops — have been a serious problem in recent years.

In Tuesday's assault, deputy provincial police chief in northern Zawzjan province, Abdul Hafiz Khashi, said that before dawn, a traitor allowed an unspecified number of insurgents into the compound at the checkpoint in Qush Tepa district, where they killed 10 soldiers. Khashi identified the soldier who enabled the attack as Mohammad Alim, saying he had obviously joined insurgents in the area.

The attackers and Alim fled the scene and security forces were pursuing them, he added.

Also Tuesday, a roadside bombing in northern Balkh province killed five police officers, including a district police chief, according to Sher Jan Durani, spokesman for the provincial police chief in Balkh, AP says.

The five were on patrol in a vehicle in Dawlat Abad district when their car struck the bomb. Three officers were wounded in the explosion.