A car bomb planted by Irish Republican Army guerrillas exploded and killed a senior Northern Ireland policeman as he and his wife set out for church. Supt. Alwyn Harris, 51, died instantly when a booby-trap bomb exploded under his car, police said. His wife was in shock but unhurt after the incident in Lisburn, headquarters of the British army in Northern Ireland. The outlawed IRA claimed responsibility for killing Harris in a statement to Belfast media. Police, meanwhile, foiled an attempted mass breakout by IRA prisoners from Belfast's top-security Crumlin Road jail.