Pakistani authorities suspect that the suicide car bomber responsible for an attack that killed three American soldiers in the restive northwest had "inside information" about their movements, as police rounded up 50 people, including some Afghans, in connection with the blast.
Police officials in Dir district of North West Frontier Province said they were investigating whether the suicide bomber had advance information that the US soldiers would be passing through Shahi Koto town, where the attack occurred on Wednesday.
Three US soldiers died in the attack, the first American military personnel to be killed on Pakistani soil. Two more US soldiers were injured.
Six other persons, including students of a girls' school and Pakistani security personnel, were also killed in the blast.
The American soldiers were travelling with a convoy of Pakistani security forces that was on its way to the inauguration of a school rebuilt with US aid after it was destroyed by the Taliban.
Authorities in Dir district have also rounded up 50 suspects, including some Afghan nationals, in connection with the suicide attack.