Gunmen kidnapped roughly 85 workers north of Baghdad, forcing them into a bus and a minivan, and later released about 30 women and children.

About a dozen people were killed across Iraq, and an Al Qaeda-led insurgent group announced that it will execute four Russian hostages.

The kidnapping of the 85 workers north of Baghdad was only the most recent case involving mass abductions.

It was unclear why gunmen seized the workers as they left the al-Nasr General Complex, a former military plant that now makes metal doors, windows and pipes.

But sectarian violence has been raging, and police noted that the assailants apparently looked at their captives' identity cards. In Iraq, it is often possible to determine someone's ethnic, sectarian and tribal affiliation from their names. The workers were thought to be mostly Shiite, while the plant is located in Taji, a predominantly Sunni Arab area with insurgent activity.

Kamel Mohammed, a plant engineer, said he saw gunmen in three sedans intercept two of the factory's buses and a minivan. The buses are used to ferry workers from the plant to the Shiite areas of Baghdad.

Police did not give the ages of the children who were released, and it was not clear what they were doing there. But some workers may have brought along their young children if they don't have anybody to watch over them at home, and other youngsters may have been teenagers with jobs at the factory.

An Al Qaeda-led insurgent group said in a Web statement that it has decided to kill four Russian Embassy workers kidnapped in Baghdad on June 3. It said Moscow failed to meet its demands for a full withdrawal of troops from Chechnya.

The statement by the Mujahedeen Shura Council came a day after the same group claimed responsibility for killing two U.S. soldiers whose bodies were found south of Baghdad.

At least one and possibly both of the soldiers was beheaded, a U.S. military official in Washington said Wednesday. The official requested anonymity because the final report on the bodies' conditions has not been formally released.

In other developments:

— Trade Minister Abdul Falah al-Soudani called for suspending trade with Australia because he said Australian security guards killed two people — including one of his guards — and wounded three after a misunderstanding at his ministry's parking lot.

— The U.S. military said Iraqi forces arrested a high-level insurgent in Baghdad. Noori Abu Hayder Al-Oqabi was wanted for running an assassination cell in the capital that was responsible for kidnapping and killing 14 Iraqi soldiers last month, it said.