A suicide bomber was killed Friday by police before he could reach an Afghan ministers home in western Afghanistan, but a second bomber detonated his explosives nearby, killing three civilians and wounding 16, a provincial governor said. An armed bomber, who disguised himself in police uniform, was shot to death by police guards as he was trying to enter the home of Abdul Karim Bahrawi, refugee minister, in Zaranj, the provincial capital of Nimruz province, Governor Gholam Dastagir said.