These gunmen, believed to be affiliated with the Islamic State (IS) militant group, opened fire on the police checkpoint in the town of Ameriyat al-Fallujah, some 40 km west of Baghdad, a police officer from Anbar provincial police, told Xinhua on condition of anonymity.
Iraqi security forces sealed off the scene and launched an investigation into the incident, the source said.
A medical source in the town, which is part of Iraq's western province of Anbar, confirmed the casualties to Xinhua.
In a separate incident, the security forces captured a suspect wearing an explosive belt at a checkpoint in Abu Ghraib area, some 15 km west of Baghdad, according to a statement from Baghdad Operations Command which is responsible for the security of Baghdad Province.
The security situation in Iraq was dramatically improved after Iraqi security forces fully defeated the extremists IS militants across the country late in 2017.
IS remnants, however, have since melted in urban areas or resorted to deserts and rugged areas as safe havens, carrying out frequent guerilla attacks against security forces and civilians.