The bomber detonated a small tanker truck at the home of police Brigadier General Ismail al-Juburi, a senior officer for Nineveh province, killing his son, nephew and sister-in-law -- and wounding 21 others, police and a doctor said.
Juburi was not present at the time of the attack, which took place in the Al-Sharqat area.
Suicide bombings are usually carried out by Sunni militants, including those linked to Al-Qaeda. Four suicide bombers struck in various parts of northern Iraq on Wednesday, killing four people.
And in Tikrit, also north of Baghdad, gunmen killed Sabhan al-Ajili, the owner of a money exchange shop, police and a doctor said.
Violence in Iraq has fallen from its peak at the height of the sectarian conflict in 2006 and 2007, but attacks remain common, killing more than 200 people in each of the first four months of this year.