HILLA, Iraq - A car bomber killed at least 17 people and wounded 65 on Thursday at a police building in the mainly Shi'ite city of Hilla, sources said, as Iraq braced for revenge attacks after US commandos killed Osama bin Laden.Iraq's army and police have been on high alert since American forces shot dead the al Qaida leader and security officials said they had received intelligence that the Sunni Islamist group's Iraqi wing would carry out revenge attacks.The suicide bomber rammed his car into the entrance of a police headquarters in the center of Hilla during a shift change at around 6:40 am, when many police officers were outside the building."It was a suicide car bomb at one of the police headquarters early this morning. So far, 17 people were killed and 65 wounded. But this is not final as there are many wounded in critical condition," Babil province Deputy Governor Sadeq al-Muhanna told Reuters."Although it is too early to pin the responsibility on one party, suicide explosions are mostly done by al Qaeda and we expect (al Qaeda) is behind this explosion. We said before and we say it again, al Qaeda will not be finished by the killing of its leader," he said.A police official in Hilla, 100 km south of Baghdad, said 16 people were dead and 41 wounded. An Interior Ministry source in Baghdad put the toll at 16 killed and 50 wounded and a hospital source in Hilla said 21 had been killed and at least 80 wounded.Iraqi officials often give conflicting tolls."These events happen on a daily basis in Iraq and nothing could prove that it has anything to do with the killing of bin Laden. These are routine events in Iraq. Security breaches, we are used to them," the Interior Ministry source said.Iraq has been a major battlefield for al Qaida since the 2003 invasion that toppled Saddam Hussein. Dozens of bombings and other attacks are still mounted each month, although US and Iraqi officials says al Qaida in Iraq has been severely degraded in recent years.