Several people were also reported injured in the explosion in the capital of Qila Abdullah district in the restive Balochistan province.
The Pak-Afghan border was closed following the explosion which sources said was a suicide bombing, Dawn said.
Geo TV reported that the explosion occurred inside the Customs House across the border on the Bab-e-Dosti (Friendship gate).
Chaman is a small town in the southwestern Balochistan province and is one of the two main crossing points for supplies for American and NATO troops fighting the Taliban in neighbouring Afghanistan.
