A U.S. military spokesman puts the death toll at up to 16. Neither figure could be independently confirmed.
The new attack happened as the men waited in line to enter a base west of the main northern city of Mosul.
Earlier today, six people, five of them policemen, were killed and 13 wounded when a suicide bomber blew up a truck against the back wall of a police station in the center of Mosul.
Later in a third attack, four Iraqi policemen were killed and nine wounded by a suicide bomber who walked into a police post at the main hospital in Mosul and blew himself up.
And in Baghdad, Colonel Riyadh Abd al-Karim, a deputy police chief, was gunned down outside his home in the eastern neighbourhood.
A neighborhood resident, Sabah Ismail, described the situation at the scene of the assassination: "The car was an Eiphia Kia. A thin man -- a very thin man -- stepped out and immediately started shooting at him and he continued to fire. Then the car left so quickly that it nearly overturned when it went around the corner."
Also today, a U.S. soldier was killed and two wounded by an explosive device in Baghdad.
(compiled from agency reports)[For the latest news on Iraq, see RFE/RL's webpage on "The New Iraq".]