Four people were killed and eight Iraqi soldiers were injured in two separate attacks in Iraq on Friday, while three people were arrested in connection with an attempt on the life of a senior police officer, dpa reported. Three civilians were killed when unknown gunmen in a helicopter opened fire on their car south-west of Kirkuk, the Voices of Iraq (VOI) news agency reported. A spokesman for the US military in Iraq told VOI he had no information on the incident. Kirkuk is a multi-ethnic province located some 250 kilometres north of Baghdad. In another incident, an Iraqi soldier was killed and eight soldiers were wounded when a bomb struck their patrol in the south of the city of Baquba, a police source told VOI. Baquba, in the restive Diyala province, is located some 60 kilometres north of Baghdad. Also on Friday, a senior Iraqi police officer said three police reservists were detained for attempting to assassinate him. Nasiriyah police chief Sabah al-Fatlawy confirmed that arrests in and investigation in an interview with VOI, but did not give the actual details of the attack. Nasiriyah is located in Ziqar province, 380 kilometres south of Baghdad.