BAGHDAD, Iraq (CNN) -- A car bombing that killed dozens Tuesday in a predominantly Shiite area of Baghdad may have been conducted by a militant trying to incite Shiite violence against Sunnis, the U.S. military said Wednesday.
Authorities said Wednesday that 63 people died in the strike and 71 others were wounded. Of the dead, four were women and five were children. Among the wounded were 11 women and 12 children.
The blast happened when a minibus detonated at a garage and a bus stop in the Hurriya neighborhood, ripping through a nearby market and buildings.
Lt. Col. Steve Stover, a U.S. military spokesman, said the military believes Haydar Mehdi Khadum al Fawadi, a leader of an Iranian-backed Shiite militant cell, was involved.
"Our intelligence, corroborated through multiple sources, is this atrocity was committed" by a cell led by al Fawadi, Stover said.
"We believe he ordered the attack to incite Shia violence against Sunnis," said Stover, who called al Fawadi a "murderous thug."
Such car bombings are a "trademark" of al Qaeda in Iraq, a predominantly Sunni militant group. But authorities said they don't believe that group staged Tuesday's attack. Watch people examine the scene of the deadly blast »
"Evidence leads us to believe the vehicle was a truck loaded with 200 to 300 pounds of an unknown bulk explosive. The type of vehicle and material leads us to ascertain this was not" al Qaeda in Iraq, Stover said.
Iraqi and American troops were at a neighborhood meeting less than 500 feet (about 150 meters) away from the scene of the blast, and a Shiite militant's initial claim of responsibility said the cell had been targeting U.S.-led coalition forces.
"If they were the target, then the bomb exploded prematurely," Stover said.
Funerals began Wednesday to mourn the dead.
U.S. diplomatic and military authorities deplored the strike and vowed to find the perpetrators. Iraqi Prime Minister Nuri al-Maliki called it a "perfidious crime" that portrays the activities of "terrorists" and "takfiris" -- a reference to Muslims who denounce others as nonbelievers.
He referred to those responsible as "defeated remnants of terrorism."
Such people "had returned to their old failing bet in trying to incite the sectarian strife in order to lift the fallen morale of their supporters after they tasted the bitterness of their successive defeats in Baghdad, Basra, Mosul and other provinces of the country," al-Maliki said, referring to battles the Iraqi military has fought against Shiite militants and the predominantly al Qaeda in Iraq militants.
Tuesday's attack came amid efforts to tamp down violence that erupted for weeks this spring in Shiite neighborhoods, where U.S. and Iraqi forces have battled militias.
Scores of people were killed and wounded in the fighting, which occurred largely in Baghdad's Sadr City neighborhood. A cease-fire went into effect last month in Sadr City, and fighting died down.
Violent incidents have dropped off in Baghdad this year, Iraqi and U.S. officials have said. Reasons for the decline include cease-fire efforts by the Mehdi Army -- a Shiite militia led by cleric Muqtada al-Sadr -- and the existence of walled-off, religiously homogeneous neighborhoods that used to be mixed.
But reports of violence in Baghdad occur regularly, with occasional major bombings and ambushes.
Other bombings with high casualty counts this year in Baghdad include pet market attacks that killed 99 on February 1, strikes in a commercial district that killed 69 on March 6 and a suicide truck blast that killed 18 on June 4.
Against the background of this week's violence, Iraq's foreign minister said Wednesday he is optimistic that his country and the United States will come to terms on a "status of forces agreement" to replace the one expiring at the end of the year.
"I'm still an optimist," Foreign Minister Hoshar Zebari said after meeting with U.S. Secretary of State Condoleezza Rice at the State Department in Washington.
"There is more flexibility on the U.S. side to reach an agreement that would be acceptable, reasonable and marketable for both of us, [for] the Iraqis and for them, too," Zebari said.
Senior State Department officials have said a key sticking point has been jurisdiction over U.S. personnel working in Iraq.
Iraq wants the Americans to be held accountable under Iraqi law, but the officials said this issue is a "red line" for the U.S. because it would never give up jurisdiction over personnel.
CNN's Jomana Karadsheh contributed to this report.