Updated

A key border crossing was closed Friday after a clash between Afghan and Pakistani forces, an Afghan police official said.

At least a dozen Afghan border security officers fought with 15-20 Pakistani troops on Thursday at the border in the southern Afghan town of Spinboldak, district police chief Haji Abdul Wasai said.

Clubs were used, and three of the Afghans were hurt, he said.

The conflict appeared to be linked to a group of people crossing into Afghanistan, but its cause was unclear, Wasai said.

Afghan officials were negotiating Friday with two representatives from Pakistan, but the border remained closed, he said.

An October bomb blast near the border gate in Spinboldak, in the Kandahar province, killed three people and wounded 20. Local officials blamed the explosion on Taliban militants who have stepped up attacks this year that often Afghan and U.S.-led coalition forces.