Srinagar, Feb. 5 -- Over 500 persons have been detained by police for questioning as security forces have launched a massive security operation across the Valley after the killing of an ex army man and injuring of his two family members in a terror attack in south Kashmir's Kulgam district.Sources said police and other security agencies have launched a massive operation against terrorists and their sympathisers across the Valley after yesterday's attack."The target of the operation is the Over Ground Workers of terror outfits and terror associates, who provide lodging and other support to the terrorists," they said.They said security forces, including the Army, J&K Police, and CRPF, have intensified efforts to track down the attackers, co...