A police spokesman says unidentified assailants killed at least six tribal police officers and wounded two others in an overnight rocket and gun attack in southwest Pakistan.

Abdullah Rind, spokesman for the Levies tribal police, said Friday that the attack took place Thursday night near the Iranian border.

He says the assailants first fired a rocket and then opened fire on a vehicle carrying the police, who were returning from a border town near Iran. He says the motive behind the attack was not clear.

No group has claimed responsibility for the attack, but separatist groups have waged a low-level insurgency in Baluchistan province for years.

Because of its closeness to Afghanistan, the province is also a hiding place for Taliban and al-Qaida militants.