Pakistani security forces detained 20 people and seized rockets and automatic weapons at the weekend during raids on tribal homes outside Quetta, police officials said on Sunday. Fifteen people were taken into custody on Sunday, while another five were arrested on Saturday night for having suspected links to militants in the restive region, Quetta DIG Pervez Rafi Bhatti said. Three rockets, 33 automatic weapons and a large cache of ammunition were seized during the raids, said provincial police chief Chahdhry Muhammad Yaqoob.During the raids police also unearthed a private prison and a "torture cell" set up by the suspected rebel tribesmen, he said without giving details. Bhatti said that the raids were on a "fort" owned by tribal chief Nawab Bukhsh Marri in the Marri Camp area. He said 1,500 policemen were involved the operation. A Pakistani flag was hoisted atop the fort. Suspected militants threw a grenade onto the grounds of a state-run radio stations late on Saturday, breaking windows but causing no injuries, Bhatti said. "A grenade thrown onto the lawn of Radio Pakistan exploded late Saturday night and broke the windows of a room located at a corner, but no one was injured," he said, blaming insurgents linked to Marri tribesmen for the attack.