A series of strong explosions shook the Iraqi capital soon after sunset Saturday, and some of them appeared to be in the center of the city. Warplanes could be heard overhead when the attack began about 7:15 p.m. local time. It was unclear what targets had been struck. Earlier Saturday, at least 20 columns of dark smoke could be seen rising from points around Baghdad after intermittent explosions were heard throughout the day. Al-Jazeera television reported that the plumes were coming from fires that Iraqis had set to oil containers around the city to obscure targets.

During the day Saturday, workers swept up glass and other debris from the streets after two days of fierce bombardments that destroyed presidential palaces, government offices and military headquarters.

As the day wore on, Iraqis were back in the streets in greater numbers than they had been since the start of the war. Small shops and restaurants reopened.

A massive explosion had rocked the center of Iraq's capital early Saturday just hours after Saddam Hussein's Old Palace was demolished by coalition airstrikes. Aircraft could be heard overhead and smoke and the sound of sirens rose from the city, thought it was unclear what had been targeted.

U.S. Gen. Tommy Franks, speaking from a command post in Qatar, said the assault on Iraq would be one of "shock, surprise, flexibility," using munitions on a "scale never before seen." The campaign was taking the fight "across the breadth and depth of Iraq" - aiming to secure bridges, airports and oil platforms, he said.

Elsewhere, U.S. aircraft bombed Iraqi tanks holding bridges near Basra, the country's second-largest city. American officials said Saddam's regime was clearly losing control.

However, U.S. and British forces will not immediately storm Basra, in an attempt to avoid bloody urban warfare, British Lt. Col. Chris Vernon said.

In Baghdad, Information Minister Mohammed Saeed al-Sahhaf addressed the Iraqi people Saturday, assuring them that the government remained in power and had repulsed the U.S.-British attacks, destroying five tanks in the process. He also said those captives taken by coalition troops were civilians, not Iraqi soldiers.

"Baghdad will remain with its head held high," Al-Sahhaf said. "The Baghdad of Saddam will remain defiant."

Al-Sahhaf said 19 missiles had been fired upon a small area of Baghdad, injuring more than 200, mostly civilians.

The air barrage came with U.S. ground troops already a third of the way to Baghdad, and with Saddam and his regime fighting to demonstrate their control of the country despite reports of surrendering Iraqi troops and the loss of strategic sites.

After the early morning blast Saturday, traffic returned to the streets of Baghdad, and workmen swept glass from the sidewalks around the badly damaged main presidential compound.

A hole the size of two ping-pong tables had been blown in the dome of the Peace Palace, though four busts of Saddam still stood on the corners of the building. The intelligence headquarters was gutted and appeared to have taken a direct hit.

Bricks, masonry and glass were strewn across the street in the al-Salhiya neighborhood.

Friday night's spectacular blasts lit up the horizon, illuminating Baghdad even as they devastated parts of the city of 5 million people. Iraqi anti-aircraft bursts winked in the darkness. At one point, the sound of a missile roared through a street before exploding into a fireball.

Defense Secretary Geoff Hoon said the attacks on the Iraqi capital were carefully calibrated not to damage civilian targets or city infrastructure.

"The lights stayed on in Baghdad, but the instruments of tyranny are collapsing," Hoon said.

Three major fires raged inside Saddam's Old Palace compound, which stretches for 1.7 miles on the west bank of the Tigris River. The compound is the official center of the Iraqi state, and home to the offices of the prime minister's staff, the Cabinet and a Republican Guard camp.

Despite the apparent setbacks, Saddam's regime was taking a hard line - denying military setbacks and verbally attacking its enemies in a show of public resolve. Al-Sahhaf lashed out at the Allies early Saturday.

"They are a gang of war criminals ... international bastards," he said. "They lie day and night. They are not human."

Iraqi Foreign Minister Naji Sabri sent a letter to U.N. Secretary-General Kofi Annan complaining that Americans targeted homes, schools, mosques and churches, Iraqi television reported.

PHOTO CAPTION

Smoke rises from the periphery of Baghdad Saturday March 22, 2003. Intermittent explosions were heard throughout the day Saturday and by late afternoon at least 12 huge columns of smoke could be seen rising from all along the southern horizon of the city. (AP Photo/Jerome Delay)