The U.S. military said in a statement Sunday that the program was "beginning to show a glimmer of success as more medium and heavy weapons are beginning to come in."
Carter said fighting in the slum has slowed considerably but that it was not clear whether the insurgents are using the pause to rearm and "re-seed" streets with roadside bombs, as occurred during a July cease-fire, or to disband.
Allawi was en route to the Sinaa soccer stadium when a mortar round struck it around 1 p.m., killing two Iraqi soldiers and an Iraqi civilian and wounding at least two others. It was unclear whether the attack was aimed at Allawi, who was scheduled to meet with members of Sadr's office and clerics at the stadium minutes later.
Iraqi guardsmen opened fire after the attack, shooting their automatic weapons randomly in response to reports of sniper fire. Two Iraqi police officers sitting in a nearby vehicle were wounded. Authorities immediately shut down the weapons handover program for the rest of the afternoon.
Allawi's convoy was diverted to a Sadr City government office building and his meetings with Sadr officials were postponed until later in the afternoon.
"I am very thrilled and pleased that things are moving in the right direction and arms are being surrendered to the Iraqi government," Allawi said after the meeting. "I call upon all Iraqi people throughout Iraq, whether in Basra, Nasiriyah, Fallujah, Ramadi or Mosul, to surrender their weapons and to respect the rule of law and to be part of the political process."
Large piles of weapons were visible at the stadium. They included hundreds of antitank mines, 14.5mm antiaircraft guns, 60mm, 82mm and 120mm mortar rounds, and artillery rounds.
Ahmed Saleh, 21, showed up at the stadium to turn in an old 60mm mortar launcher. Saleh, who said he was a member of the Mahdi Army, said the launcher was "not very good. I have another one at home that is much better."
Asked if he planned to hand it in, he said: "No, I'm going to keep it."
Special correspondents Bassam Sebti, Khalid Saffar and Omar Fekeiki contributed to this report.
