A member of the Afghan National Police opened fire and killed at least 10 of his colleagues at a checkpoint in southwestern Afghanistan Saturday, officials said.

The killings come a day after two Afghans, including a police officer, shot and killed six U.S. service members in separate attacks in neighboring Helmand province in the volatile south.

Afghan attacks on their international partners are on the rise and have heightened mistrust between foreign forces and Afghan soldiers, police and others they are training and mentoring.

Cases where members of the Afghan security forces kill within their own ranks are rare, but have been reported in the past.

Shakila Hakimi, a member of the Nimroz provincial council, said the policeman is believed to have links to militants. He opened fire on his colleagues in Dilaram district.

The policeman was killed in an ensuing gun battle, she said. "The checkpoint is in a remote area of a remote district," Hakimi said. "The telecommunications are poor and we are not able to get more details."

Hakimi said the provincial governor has sent a team to the scene to get more details about the incident.