Some unknown militants, riding a bike, Friday hurled a hand-grenade inside the office of a US-based NGO, Save the Children (STC), in Southwestern Pakistani province of Baluchistan, said official sources. Sources told KUNA that there were no casualties but the explosion badly damaged the office, located in Chaghi district, about 335 kilometers west of Quetta, the provincial capital. They said explosion smashed window glasses, damaged walls and furniture of the office. Sources did not blame any group but pointed finger at nationalist militants.Local Baluch nationalist militants carry such terrorist attacks on government and foreign buildings as well as security force for their cause of maximum provincial autonomy and increase in royalties.