MOSUL-A car bomb and a shooting in north Iraq killed four police and wounded 15 other people Sunday, police and a doctor said. The car exploded as security forces searched a home near the northern city of Mosul, killing three police and wounding 15 people, while gunmen killed a fourth policeman in the city, the sources said. Iraq is struggling to contain a wave of violence that has killed more than 430 people so far this month-the second month in a row in which more than 400 people have died in unrest. Violence in Iraq has decreased from its peak in 2006 and 2007, but attacks remain common, killing at least 200 people each month this year.