According to Al-Riyadh newspaper, an Indian who was kidnapped by the terrorists and forced to help them, tipped off the security officers about the present location of the militants.[Sify, via The Agonist]
Well done, Unknown Indian.
As the Religious Policeman has been telling us, the Saudi authorities are not doing all that well in their fight against terrorists. He suspects the involvement of influential royals or the complicity of security forces behind the poor record of successes.