An explosion Monday morning outside a police station killed at least 9 people and devastated a working-class street in southwest Baghdad, killing Iraqis who wash cars and sell car parts in the dusty neighborhood.

Reports of the death toll varied from 9 to 15, with as many as 50 wounded. More than a dozen policemen lining up for the morning shift change were injured.

"This was a cowardly attack. These are laborers who come here. These terrorists just want to destabilize Iraq," said a national guardsman, Hassan Kareem, who was at the scene of Monday's blast.

Witnesses differed as to the cause of the attack. Some said a vacant car blew up. Others swore it was a rocket attack. Lt. Col. William Stallings, part of an American patrol that arrived on the scene, said "we believe it was a fuel truck. That explains the size of the hole."

The explosion left a large crater in the dirt street, approximately 12 feet deep and 20 feet wide. "I was starting to work at the garage, when I saw a car coming toward me," said Adnan Mehdi, 26. "He came down the street and suddenly there was an explosion."

As often happens, some in the crowd claimed that the explosion was caused by an American bomb. They began to shout anti-American slogans, drawing more into the shouting. "Damn the Americans. Where is our god?" yelled two black-clad women at the center of the crowd.

But when the crowd began shouting pro-Saddam Hussein slogans, that inflamed the national guardsmen. They began shooting volleys into the air, scattering the group.

At the outskirts of the crowd, another woman in black, wept. Her husband was a tea-seller who had worked on the street for 15 years, and her son washed cars in the adjoining shop. "Where are they? Where are they?" she wailed. "I feel in my heart something terrible has happened to them."

U.S. Army Lt. Col. Bill Salter told wire services that between 10 and 15 people were killed and more than 40 wounded in the attack Monday. Iraqi officials put the total dead at 9, with at least 50 injured.

The violence Monday and last week followed a period of comparative calm after the United States transferred political authority to the interim Iraqi government on June 28.

In addition to the attacks on police stations in Baghdad and in the city of Haditha, insurgents have hit oil pipelines in the north and south of Iraq and have attempted to assassinate Iraqi officials, including the minister of justice over the weekend.

Barbash reported from Washington.