The mishap happened after a suicide bomber detonated his explosive belt at the Pak-Afghan border in the Chaman town, The Express Tribune reported.
The bomber blew himself up in a parking area where the North Atlantic Treaty Organization (NATO) trucks were waiting for the document verification.
The Pakistan Police confirmed the attack and said, "A pedestrian came close to a vehicle of security forces near the parking lot and blew himself up."
"At least 22 people were injured in the blast," Assistant Commissioner Kashif Nabi said.
The injured were taken to the District Headquarters Hospital for medical assistance.
"We have received 22 injured with burns and wounds caused by splinters. A 12-year-old boy succumbed to his serious injuries during treatment," a hospital source said.
Three men with critical injuries were referred to a hospital in Quetta for treatment.
The border was closed soon after the blast, which was opened only a day ago.
Earlier, at least 50 people were killed or wounded in a similar attack, when a suicide bomber attacked the Pakistan Army in the city. (ANI)