U.S. sources describe a "second ring" of regular Iraqi defenses around the city, apparently a protective perimeter. These sources said coalition forces may not encounter much more of an Iraqi defense before U.S. troops get to the capital. 

Electrical power went out in large sections of Baghdad shortly before 9 p.m. (noon EST) after having remained on through nearly all of the two-week bombardment of the city. The blackout appears unrelated to the bombing. A series of explosions in the city followed the outage, a source in Baghdad told CNN's Nic Robertson. 

In Washington, the chairman of the Joint Chiefs of Staff, Gen. Richard Myers, said he did not know the cause of the blackout. U.S. Central Command "has not targeted the power grid in Baghdad," he told reporters. "We do not." 

The Iraqi Special Republican Guard and members of Iraqi President Saddam Hussein's security services are stationed in the city. 

The U.S. Army's V Corps and 1st Marine Expeditionary Force were leading the advance, reporting minimal resistance as they closed in on the city. 

CNN's Walter Rodgers, who is embedded with the 3rd Squadron, 7th Cavalry of the U.S. Army's 3rd Infantry Division, said that small groups of 10 to 20 Iraqi troops -- hiding in foxholes and behind other cover -- have been firing on the advancing U.S. tanks and armored vehicles from both sides of the road. (On the scene) 

The Bradley fighting vehicle crews responded, firing their 29 mm guns. 

Rodgers said that the squadron passed a number of burned-out Iraqi vehicles, including outdated, Soviet-era Iraqi tanks and armed pickup trucks and that the bodies of dead Iraqi soldiers dotted the landscape. 

"What we noticed was all the dead Iraqi soldiers had gas masks, as if they are indeed preparing for chemical attack," Rodgers said. 

U.S. officials emphasized that the coalition may be approaching the most dangerous stage -- the "tipping point" when the Baghdad regime feels it may soon lose power. 

Two indicators are emerging: Officials said recent information confirms "high" potential for the use of chemical weapons, and there is also intelligence that Saddam's regime may begin to attack areas in Baghdad, killing civilians and blaming the United States. 

Iraqi Information Minister Mohammed Saeed al-Sahaf, however, called reports of coalition forces on the outskirts of Baghdad "an illusion." 

"They're not even [within] 100 miles," he said. "They are not in any place. They hold no place in Iraq. This is an illusion. ... They are trying to sell to the others an illusion." 

In northern Iraq, hundreds of Kurdish troops are securing an eight-mile (13-kilometer) stretch of road Thursday between Kalak and Mosul, the largest city in the area under the control of the Baghdad government. 

The Kurdish soldiers are filling a vacuum left by Iraqi soldiers, who suddenly pulled back Wednesday afternoon from the ridge overlooking Kalak. 
 

Behind the leading edges of the coalition advance, other U.S.-led troops battled remnants of Iraqi forces to secure areas, cities and strategic facilities from the Persian Gulf northward to Karbala, about 50 miles south of Baghdad.  The 101st Airborne Division took control of Najaf and isolated Iraqi forces in that area, the U.S. Army said. Around the southern city of Samawah, the 82nd Airborne Division tightened its grip on paramilitary forces, attacking a platoon attempting to organize north of the city, the Army said.  Special Operations forces raided a palace roughly 56 miles outside Baghdad that is a known residence of Saddam and his sons, Brig. Gen. Vincent Brooks said Thursday during a briefing at U.S. Central Command headquarters in Qatar.  Brooks said that U.S. forces did not capture any Iraqi leaders at the Lake Tharthar Palace but did find documents that could provide useful information.  Special Forces located several bridges and a dam wired with explosives, according to Central Command.

U.S. Marines carry a wounded soldier to a helicopter for evacuation to a mobile surgical hospital after two convoys collided on a road south of Baghdad on Thursday.

Other developments
• President Bush traveled to Camp Lejeune, North Carolina, to speak to a crowd of some 20,000 people and to meet with families of Marines killed in action in Iraq. The White House said that 11 Marines from Camp Lejeune have died in action in the war and a handful are listed as missing in action. Bush thanked the Marines and their families for their sacrifices. He vowed, "We will accept nothing less than complete and final victory" in the war in Iraq. "The course is set. We're on the advance. Our destination is Baghdad." 

• Grand Ayatollah Sistani, whom Iraqi authorities in Najaf had held under house arrest, was released and issued a fatwa calling on Iraqis not to interfere with coalition forces, Brooks said Thursday. Last week, while in Iraqi custody, Sistani had issued another fatwa urging Muslims to resist. 

• The New York-based group Human Rights Watch condemned Iraq for placing antipersonnel landmines in and around a mosque, calling the action a violation of international humanitarian law. The group said Iraq stored antipersonnel landmines inside a mosque in Kadir Karam in northern Iraq and placed them around the mosque before abandoning the area March 27. • Rescued Army Pfc. Jessica Lynch, 19, arrived in Germany late Wednesday for treatment of injuries at Landstuhl Regional Medical Center. U.S. forces launched a pre-dawn raid Wednesday to rescue Lynch from a Nasiriya hospital used as an Iraqi military post. She had been listed as missing in action after intense fighting near Nasiriya on March 23. Central Command said 11 bodies also were discovered. Lynch, who is in stable condition, will undergo surgery Thursday on a fractured disc in her back, a family spokesman said. 

• Informants have told U.S. Marines that Gen. Ali Hassan al Majeed, Saddam's cousin, recently conducted meetings of the Iraqi resistance in the same hospital where Lynch was held prisoner. It was also reported that al Majeed has been driving in southern Iraq in an old red car, possibly a 1979 Nissan. Al Majeed is widely known as "Chemical Ali" for ordering Iraqi forces to use chemical weapons on Kurds in northern Iraq in 1988. 

• British forces late Wednesday and Thursday bombarded Iraqi forces around Basra with long-range artillery. A British military spokesman said the situation around Iraq's second-largest city was "stabilizing by the day." 

• The Qatar-based, Arab-language TV news network Al-Jazeera reported Wednesday it has suspended the work of all correspondents in Iraq after Iraqi officials banned at least one of its employees from reporting.

• The United Nations warned Wednesday that humanitarian food rations handed out by coalition forces in Iraq have a wrapping the same color as unexploded bomblets dropped in the country. It cited concerns that children who confuse the two could be at risk for death or injury.

• The fate of those aboard a U.S. Army Black Hawk helicopter remains unclear Thursday after the chopper went down Wednesday night near Karbala in south-central Iraq. The Pentagon said seven soldiers were killed and four others wounded and later rescued. But a Central Command statement said six people were on the Black Hawk and that casualties could not be confirmed. 

• U.S. officials also said that a U.S. Navy F/A-18C Hornet went down over Iraq early Thursday and a search-and-rescue operation was under way for the pilot, who ejected. U.S. military officials confirmed that they are investigating whether a U.S. Patriot missile may have mistakenly shot down the plane.