Iraqi man, injured in explosion at Mereidi market grimaces in pain in al-Sadr hospital, in Shi'ite enclave of Sadr City

Some 40 people were killed or found dead in Iraq Thursday, including seven who died in a bomb blast in Baghdad's Sadr City.

Forty-five other people were wounded in the blast. Officials say a motorcycle rigged with explosives blew up in a market.

The attack came a few days after Iraqi Prime Minister Nouri al-Maliki ordered the lifting of a U.S.-Iraqi security blockade in Sadr City, a Shi'ite stronghold. The blockade was part of a search operation for a missing American soldier, whom U.S. officials believe was kidnapped last week by Shi'ite militants.

The U.S. military said Thursday the missing soldier is still being held by his captors. A spokesman, Major General William Caldwell, said there are ongoing talks aimed at freeing 41-year-old Ahmed Ausaid al-Taayie, who is of Iraqi descent.

In other violence Thursday, insurgents shot dead a dean at Baghdad University, as well as his wife and son. Gunmen also kidnapped two sports coaches for disabled athletes.

And the U.S. military said a coalition air strike killed an influential leader of al-Qaida in Iraq in the western town of Ramadi on Wednesday. A statement said a laser-guided bomb destroyed a car carrying Rafa Abdul Salam Hamud Al Ithawi and his driver, killing both men.