There was an explosion. A deep crater proved it. Beyond that, the facts were murky.

The blast outside a police station Monday morning in Baghdad illustrated how, in this land of confusion, there is seldom a version of the truth that is accepted by everyone. Of those at the scene, each person left with his or her own version.

In a few minutes, a suicide vehicle bombing was somehow turned into an insidious air attack by U.S. planes. As the crowd was swept up in that theory, it became the truth for them, for the moment. Anti-American chants grew, cameras gathered, fists waved in the air.

In news broadcasts, much of the Arab world would see that scene: Iraqis appearing angry and aggrieved, insisting that those killed were the martyrs of American aggression.

Here is how that happened:

The primary evidence of the explosion was a gaping hole in the dirt street behind a large police station in a working-class neighborhood. The pit, about 12 feet deep, was charred and still expelling an acrid smoke when it began to fill with oily water from firetrucks. If a vehicle had stood on that spot, it had been tossed far away. Many blackened wrecks nearby were possible suspects.

The scene was a dusty lane tucked between low lines of tin-roofed carwash bays and concrete structures where auto parts are sold, all of which serve the vehicle repairmen working around the neighborhood. Men with oil-stained clothes, hands rough from the pull of a wrench, stood listening to the accounts.

"I was starting to work at the garage when I saw a car coming toward me. He came down the street, and suddenly there was an explosion," said Adnan Mehdi, 26.

No, no, insisted another, a round young man: "We saw a helicopter hovering over our head. An American helicopter. It was right after that that we heard a very big explosion. The helicopter shot something."

"I don't think it was a car bomb. The crater was too big," agreed a policeman nearby.

"It was a rocket," an older man in a white robe exclaimed with abrupt conviction. "I saw it fall. I saw it come from an F-16 overhead. I saw the fighter throwing the rocket." He began to race around, flapping his arms, animatedly recreating this vision.

His claim spread quickly. It reached two women, draped in black abayas, their heads covered. They were older women, with thick faces and hostile eyes. They began muttering loudly, then speaking louder. Soon they were haranguing the crowd, shouting curses and damnation at the Americans and demanding to know what they were doing in Iraq.

The women thrust their arms to the skies, their surprisingly strong voices gripping the crowd. "Where are the true Arabs?" shouted one. "Where is our God? God is great!"

Voices joined theirs, shouting "God is great." The message turned political: "We will avenge you, Bush. Why do you kill our young men?"

Television cameras turned toward the women. Young men and boys began jostling behind them to get into the picture, grinning before they donned a serious pose. They took up the chant, then uttered a new one: "Saddam! Saddam! We sacrifice our blood for you, Saddam!" The women ululated in a high-pitched warble.

It was too much for the Iraqi National Guardsmen at the scene, sweating and frustrated as they tried to move the crowd away. One raised his rifle, swearing at the people to get back. He shot into the air, a jolting crack that seemed a signal for a dozen others to fire. The staccato of their rifles blended to a thick, roaring volley as people ducked and ran in confusion.

A policeman leapt to the open passenger door of a patrol truck as it swerved around the lot. Waving his rifle wildly, he hung from the door and shouted at the crowd, "Come close and I will shoot you."

U.S. troops, determinedly playing the role of a backup force to the new National Guard, watched warily. American officers tried to get the guardsmen to form an orderly line to corral the crowd, but it fell apart in disarray. The head of the U.S. force, Lt. Col. Bill Salter, stuck to his talking points.

"The Iraqi security forces are helping get the situation stabilized," he said, standing in the midst of chaos. "They are doing a great job."

Asked if he approved of the gunfire, Salter observed dryly, "It's not what we like to train."

Off to the side, an old woman sobbed, her eyes covered by hands tattooed in traditional henna. Her husband, who owned a tea cart, and her grown son, who washed cars, were missing, she cried.

The men around her looked down and shuffled their feet. They would not tell her the truth -- that they had seen the lifeless bodies of her husband and son, burned and broken.

One man, taking her gently by the hand, suggested: "Let us go to the hospital and look."

The U.S. military suspects a fuel tanker was used in the suicide truck bombing in Baghdad, but suspicious Iraqis asserted that the blast was caused by a U.S. helicopter or fighter jet.