The attack came just two days after a twin suicide attack claimed by Daesh killed 32 people in the capital.
At least 11 fighters from Iraq's state-sponsored Hashed al Shaabi force have been killed in an ambush by Daesh north of the capital, said Hashed security sources.
The militants used light weapons and the cover of darkness to target the Hashed east of Tikrit, the capital of Iraq's Salahaddin province, two days after a twin suicide attack claimed by the group killed 32 people in Baghdad.
"IS [Daesh] launched an attack on the Hashed's Brigade 22," said one of the unit's officers Abu Ali al Maliki.
Maliki said the brigade commander was among those killed before reinforcements from the federal police came to the unit's aid.
Hashed security sources said the total toll was 11 dead and 10 wounded.
Security sources blame Daesh
There was no immediate claim of responsibility, but security sources interviewed by AFP blamed Daesh.
Local and Western sources have expressed concern over the readiness of Iraq's security forces, who have been worn down by the spread of Covid-19, political infighting and corruption.
This week's attacks may be more illustrative of those accumulated shortfalls than any significant Daesh comeback.
Iraq declared the group territorially defeated in late 2017, but has continued to battle extremist sleeper cells, mostly in the country's mountainous or desert areas.
READ MORE: Why suicides have spiked in Iraq