Two separate suicide bomb attacks have killed three people and injured 21 in the northern city of Mosul, said An Iraqi official Saturday. Spokesman Brig. Gen. Khalid Abdul-Sattar says a suicide bomber detonated an explosives-laden car near an Iraqi army checkpoint after soldiers began firing at him. Saturday's attack killed three soldiers and wounded six civilians. The spokesman said half an hour later, another suicide attack occurred elsewhere in Mosul when a bomber detonated his tanker loaded with explosives near a different Iraqi army checkpoint. He said that blast injured 15 civilians, mostly occupants of vehicles in traffic. The US military says Mosul is the last urban stronghold of al-Qaida in Iraq.