BAGHDAD, Iraq — Two days after Prime Minister Nouri al-Maliki called the opening steps of a security crackdown here a "dazzling success," two car bombs tore through a crowded market and killed at least 60 people on Sunday.
The attack occurred only minutes after American soldiers passed through the area on patrol, underscoring the difficult nature of trying to quell violence on Baghdad's streets, where car bombs have been an almost daily occurrence and suicide attacks directed at civilians are so common that many of the markets have been closed to vehicle traffic in recent days.
The blasts on Sunday occurred in the mostly Shiite neighborhood of New Baghdad, devastating an open-air market, setting dozens of cars ablaze and causing the partial collapse of a two-story building that housed several electronics stores.
The street was littered with charred televisions, satellite dishes and small generators. Shattered blue tiles, glass and blood were trampled together as the survivors tried to rush the more than 131 people wounded in the attack to the hospital. They wrapped the dead in rugs and blankets and whatever else they could find.
The explosions occurred within seconds of each other, according to witnesses, and were probably detonated in cars already parked in the area, Iraqi officials said.
Abdul Hussein Ameer, 41, said he ran when he heard the first blast shortly after 3 p.m.; he said he was so familiar with the pattern of the bombers that he knew another explosion was likely. But before he could get out of his shop, where he sells plastic containers and dishes, the second bomb exploded.
"I hold the American forces responsible for this," he said, black soot on his face and clothes. He said that they were in the area only minutes before the blast and yet were unable to stop it.
Fifteen minutes before the attack, a joint patrol of American soldiers and Iraqi policemen had stopped on the corner where the second bomb exploded, posing for pictures, according to a Reuters photographer who was embedded with the American unit.
President Bush has acknowledged that such attacks would be nearly impossible to eliminate. He said in a news conference last week that the immediate goal of the security plan was to establish "relative peace."
Another car bomb on Sunday hit a police checkpoint in the Shiite stronghold of Sadr City, killing two people, including a police officer, and wounding 11, Iraqi officials said.
Maj. Gen. Joseph F. Fil Jr., commander of the multinational force in Baghdad and of the 1st Cavalry Division, said Friday that one tactic to try to stem the bloodshed was to limit access to the major markets — where Iraqis shop for essential goods — to pedestrians.
Residents and witnesses said the market where the attack occurred Sunday had already been closed to traffic, and they were at a loss to explain how the attackers were able to get into the area.
The attackers were probably Sunni Arab militants, American and Iraqi officials said, seeking to fuel the sectarian tensions that have torn Baghdad apart. They have responded to past security pushes in similar ways: with bursts of bombings and other attacks seemingly calculated to undermine efforts by the Americans and the Iraqi government to provide a sense of security and confidence for families here.
American and Iraqi forces have increased their visibility throughout the capital in the past four days, and there have been reports that many militiamen have been lying low or have left in anticipation of efforts to carry out the security plan.
There are dozens of new checkpoints throughout the city, and overhead, fighter jets can be heard flying over Baghdad all day long, a reminder of the American presence.
Before Sunday, there had been a relative lull in extreme violence in the capital after the Iraqi government officially announced the start of the crackdown on Wednesday. On Friday, in a videoconference with Bush, al-Maliki reported progress in glowing terms, calling the early days of the security plan a "dazzling success."
On Saturday, the government announced that there had been an 80 percent drop in crime and reported Sunday that 300 people displaced from their homes because of sectarian fighting had been able to return. American officials have been much more cautious than Iraqi politicians and military commanders, trying to damp expectations for immediate results.
Fil said the recent respite in violence was probably related to the militants' need to figure out what the new strategy entailed. "They are watching us carefully," he said.
Beyond setting up checkpoints, American troops are reinserting themselves in neighborhoods in ways that they have not done since the earliest days after the invasion, establishing a series of joint security stations where they are living with and fighting alongside Iraqi forces.
The increased presence has come with increased risk, putting more American troops in the direct path of sectarian battles on Baghdad's streets. On Saturday, two American soldiers were killed in separate attacks in and around the capital, the military said Sunday.
But American and Iraqi officials also pointed to recent successes that they attributed to the stepped-up military campaign.
Over the past year, it has been common for as many as 50 bodies to turn up in the street each day, showing signs of torture and indications that the victims had been killed at close range. In the past two days, only eight bodies have been recovered, according to Iraqi officials.
The Americans also announced Sunday that they had captured a militant who they believed to be responsible for planning a series of car bomb attacks directed at civilians. After receiving reports that the suspect was using an area hospital as a haven, they conducted an early morning raid in the Adhamiya district of Baghdad on Saturday and were able to detain him, the military said in a statement.
The American military said early Monday that they had detained 49 terrorism suspects in a small village south of Baghdad called Quarghuli. The military said the operation lasted two days and included both ground assaults and air attacks; American troops came under small-arms fire but no casualties were reported.