Brig. Gen. Ali Aouni, the head of the Iraq Defense Ministry's intelligence academy, and his bodyguards were killed when the bomber detonated his explosive vest just as Aouni was leaving his house in Tal Afar, 420 kilometers (260 miles) northwest of Baghdad, police said.
The suicide bomber, who was waiting outside of Aouni's house, told the guards that he wanted Aouni to help him on some matter. When the guards opened a gate to let Aouni's car through, the bomber blew himself up.
There was no claim of responsibly for the attack, but it bore the hallmarks of al-Qaida's local franchise, which often uses high profile-killings to sow fear and undermine the government's authority. Violence has decreased in Iraq, but insurgent attacks are still frequent.
A medic in Tal Afar hospital confirmed the death toll.
All officials spoke on condition of anonymity because they were not authorized to talk to media.