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According to a private news channel, the blast took place at the mountainous Tirah valley, near the Afghan border.
The vehicle was completely destroyed in the blast while it was not clear who planted the bomb in the vehicle.
At least four suspected militants were killed while another was injured in the incident.
Supporters of a militant group "Lashkar-e-Islam" and rival faction "Ansar-ul-Islam" routinely target each other mainly because of their sectarian thoughts.
Hundreds of people from both sides have been killed in their bloody conflicts over the past few years.
Copyright NNI (News Network International), 2011