"An ICDC member was killed and four others wounded when an improvised explosive device blew up against their vehicle," Ibrahim Abd Allah Jassim told AFP.
Four suspects were detained from an area near the site of the explosion and are undergoing questioning, he said.
Meanwhile, a US soldier and two Iraqi security personnel were wounded when a homemade bomb exploded as they patrolled central Baghdad on Wednesday, US Army Colonel Peter Jones said.
Three other Iraqis were wounded when a mortar round fell on an ICDC base in Mosul overnight on Tuesday, according to ICDC officer Mijbal Ali Hammadi.
Also on Tuesday, at least two children, aged three and seven, and an elderly woman were killed after an explosion rocked a Baghdad neighbourhood.
Local residents said US artillery fire shook the al-Dura area, injuring another two civilians and destroying three homes.
US occupation forces use so-called "harassing" artillery fire in an attempt to curtail the movements of Iraqi resistance fighters.
But many Iraqi civilians say that these US shells often go astray and hit their homes.
Also on Wednesday, US and Iraqi military forces launched an operation in Baghdad to weed out occupation fighters and seize illegal weapons with troops, helicopters and armoured vehicles raiding a suspected arms market.
The campaign comes a day after gunmen killed two Europeans working on a water project. This week, assailants killed four American missionaries also working on a water project.
At least two children were killed
in a rocket attack on this home
The operation launched on Wednesday is called "Iron Promise" and is expected to involve thousands of US troops from the Fort Hood, Texas-based 1st Cavalry Division, which has recently arrived in Iraq, and the outgoing Germany-based 1st Armoured Division. Scores of Iraqi Civil Defence Corps soldiers are also involved.
In the first raid, about 250 troops from the armoured division's 1st Squadron, 1st Cavalry Regiment as well as 250 Iraqi soldiers fanned out across the sprawling 20th Street Market, in the city's Al-Bayaa district, which sells everything from vegetables to used car parts.
In one car repair shop, US troops found a pair of rocket-propelled grenade launchers and burlap sacks full of grenades. They arrested three men.
Some stores are suspected of supplying weapons to "rebels", said the raid's commander, Lieutenant Colonel Chuck Williams. He said the market assault was the start of a citywide crackdown on the fighters.
"There is a lot of pressure everywhere. It is all over town. The big things we are looking for is people moving weapons, IED (improvised explosive device) materials and explosives and ammunition. Our soldiers are looking to deter or discover this activity. We want to shut it off," he said.
With helicopters hovering overhead, forces in Bradley fighting vehicles and Humvees circled the market to prevent fighters from escaping. Troops then went store to store searching for weapons and suspects.