A wave of clashes in Afghanistan killed more than 70 people, including 18 policemen and four Canadian soldiers Friday, officials said, amid alarm about the country's mounting Taliban-led insurgency. The growing unrest has led Washington to deploy 17,000 more troops to Afghanistan, due in the coming weeks, in a move a NATO general said would trigger more violence but would help improve security in the longer run. The four Canadians, part of the international assistance force, were killed in two separate explosions that also killed an interpreter and injured eight soldiers and an Afghan national, the Canadian military said. The first incident happened at 6:45 am local time, Brigadier-General Jon Vance, the Canadian commander in Kandahar, said in an address televised in Canada from a base in southern Afghanistan.