Police acting on a tip have arrested at least 17 people and seized a major cache of weapons near the Sri Lankan capital, Colombo. Authorities say the weapons confiscated by police Saturday included grenades and other explosives. Officials say the suspects were planning a major attack on the capital. The find comes on the same day a bomb blast killed six soldiers and wounded several in the northern Jaffna peninsula. The improvised device exploded as soldiers cleaned up the area after a failed attempt by Tamil Tiger rebels to capture the peninsula.Meanwhile, the Tamil Tigers released a policeman who had been held for nearly a year after he strayed into rebel territory while pursuing a pedophile. His release followed a request from Ulf Henricsson, the outgoing head of the team monitoring the 2002 ceasefire between the government and rebels.