Kidnappers have abducted one American and one Canadian in the northern Nigerian state of Kaduna, killing two police officers, a police spokesman said on Wednesday. The American and Canadian were ambushed by unknown gunmen around Kagarko on their way from the city of Kaduna to the capital Abuja, Reuters quoted Mukhtar Aliyu, a spokesman for the Kaduna state police, as saying. The two police escorts attached to them engaged the kidnappers in a gun battle, according to Aliyu.