BAGHDAD, Iraq — A Jordanian who killed two U.S. soldiers last month was fatally wounded in a clash with security forces, a senior Iraqi official said today.

Diyar Ismail Mahmoud, known as Abu al-Afghani, was identified as the killer of the two soldiers, National Security Adviser Mouwafak al-Rubaie told reporters. The two soldiers' mutilated bodies were found after they were captured in a clash near Youssifiyah, southwest of Baghdad.

A third American was killed in the clash. Al-Rubaie did not say when Mahmoud was wounded or died.

In other violence, a suicide car bomber detonated explosives in a crowd of laborers gathered across the street from a major Shiite shrine in southern Iraq today, killing at least 53 people and wounding 105, officials and witnesses said.

The attacker drove a minivan to where Shiite laborers gather daily to look for work in Kufa, 100 miles south of Baghdad. He offered them jobs, loaded the minivan with volunteers and then detonated the vehicle, Najaf Gov. Asaad Abu Kalal told a Shiite television station.

Kufa is a stronghold of radical anti-American cleric Muqtada al-Sadr, whose movement controls the mosque. It appeared the blast was aimed at undermining al-Sadr's position in Iraq's sectarian struggle, much of which has been blamed on al-Sadr's Mahdi Army militia.

The blast occurred one day after gunmen killed at least 50 people in a major assault on a market in Mahmoudiya, 75 miles north of Kufa.