Iraqi officials say a suicide bomber driving an ambulance killed at least 12 people in an attack on a security service training center in central Diyala province.
Local officials say at least 50 people were also wounded in the blast Wednesday.
It was the second suicide attack on Iraqi security forces in recent days.
On Tuesday, a suicide bomber blew himself up in a crowd of police recruits in Saddam Hussein's hometown of Tikrit, killing at least 50 people and wounding 150 others.
Local officials blamed the attack on members of al-Qaida.
Some information for this report was provided by AFP, AP and Reuters.