A car bomb exploded outside a police academy in northern Iraq on Sunday, and when police set up a checkpoint to close off the area, a second car bomb exploded nearby, authorities said. At least six Iraqis were killed and 25 wounded, a hospital official said. The coordinated attack in Tikrit, occurred just as new police recruits were about to leave the academy and travel to Amman, Jordan, for a training program, said police Lt. Shalan Allawi. Tikrit is 80 miles north of Baghdad. At Tikrit General Hospital, Dr. Mohammed Ayash said four policemen and two civilians were killed by the bombs, and 23 policemen and two civilians wounded. South of the capital, three insurgents were killed Sunday as the roadside bomb they were trying to plant in the town of Mahawil exploded, police said in the nearby city of Hillah.