At least 11 people were killed and eight wounded late on Sunday night when militants launched an orchestrated attack on an Iraqi military post in western Baghdad, police said on Monday.
A government statement put the death toll at four, with three wounded.
About 11pm local time, ISIS gunmen opened fire on a monitoring tower in Al Radhwaniyah district, guarded by Sunni paramilitary troops, one of whom was killed and another wounded, a tribal leader said.
The wounded started making calls for support from their base about a kilometre away.
“Whoever rushed to the scene was either killed or wounded and had his car burnt,” the tribal leader said.
“The clashes were fierce. Daesh militants were yelling ‘Allahu Akbar’ and fire was coming from three directions.
“They used light weapons, grenades and roadside bombs to attack those rushing for help."
A security source said: "ISIS attacked the monitoring tower, killing five members of the tribal Hashed and six local people who had come to help repel the attack."
A medic said eight of the wounded were transferred to a hospital in central Baghdad.
The militants fled the scene shortly after the attack. The army and police are search for the assailants.
There was no immediate claim of responsibility from ISIS.
Nearly three years after declaring victory over ISIS in late 2017, Iraqi and American officials are still warning that the war with extremists is far from over.
Iraqi officials say ISIS remnants, mainly locals, are regrouping in small numbers in rural areas of the centre and the north.
They are carrying out guerrilla-style attacks and posing a challenge to Iraqi security.
At its height, the group overran nearly a third of Iraq and Syria between mid-2014 and late 2017.
Thousands of militants joined from around the world.