BAGHDAD -- Iraqi and American forces killed several hundred fighters apparently trying to ambush religious pilgrims in the holy city of Najaf , during a day long battle yesterday in which a US helicopter crashed, killing two US troops, Iraqi security officials said.
The fighting, on the eve of the Shi'ite Muslim holiday of Ashoura, occurred as a mortar attack killed five teenage girls at a school in Baghdad and the daily civilian death toll nationwide again climbed past 100.
Iraqi security officials offered conflicting accounts of the identity and motives of the heavily armed fighters in Najaf, variously de scribing them as foreign fighters, Sunni Arab nationalists, loyalists of executed former dictator Saddam Hussein, or followers of a messianic Shi'ite death cult. Some witnesses reported the attackers wore colorful Afghan tribal robes.
The cause of the helicopter crash in Najaf was unclear, but US and Iraqi officials said it was felled by fire from the ground, and witnesses said they saw it shot out of the sky. It was the third helicopter to go down in eight days.
Three more US troops were reported killed yesterday, and at least 113 Iraqis were killed or found dead.
Yesterday's fighting in Najaf and elsewhere was extraordinary, even by Iraq's bloody standards, highlighting the daunting challenge faced by US and Iraqi forces, which are fighting a complex patchwork of elusive enemies, including Shi'ite militias and Sunni Arab insurgents.
Iraqi security forces took authority over Najaf's security about a month ago. But witnesses and security officials said yesterday that Iraqi forces were being beaten by the enigmatic but well-organized fighters until US forces and air support arrived.
Shaky footage recorded by cellphone, broadcast on Iraqi television, showed Iraqi soldiers hunkered behind a berm as intense gunfire erupted and smoke rose in the distance.
Ali Nomas, an Iraqi security official in Najaf, said the fighters belonged to a group calling itself Heaven's Army -- one among several messianic cults that have appeared among Shi'ites, who believe in the imminent return of Imam Mahdi, the last in the line of Shi'ite saints who disappeared more than 1,000 years ago. Nomas said the information came from interviews with at least 10 detained fighters.
"Every day someone claims he's the Mahdi," he said.
Nomas said the leader of the previously unknown Heaven's Army had told followers that he was a missing son of the Imam Ali, the cousin and son-in-law of the Prophet Muhammad. Ali's remains are entombed in Najaf.
"They believe that the Mahdi has called them to fight in Najaf," he said, adding that fighters had converged on Najaf from other predominantly Shi'ite cities in Iraq.
Nomas lamented that the death and destruction in Iraq had convinced some Shi'ites that the end was coming. "There's nothing bizarre left in Iraq any more," he said in a telephone interview. "We've seen the most incredible things."
But Governor Asaad Abu Gulal of Najaf said some of the fighters were members of Hussein's Ba'ath Party.
Although they disagreed on the attackers' identity, Iraqi officials and witnesses offered the similar account of events on the battlefield. Most of the fighting took place in the farmland outside the city, home to the most revered Shi'ite cleric, Grand Ayatollah Ali Sistani. Security forces cordoned off the ancient labyrinthine city to prevent attacks on pilgrims, clergy, and holy sites, the governor said.
The gunmen, numbering at least 500, planned to launch their attack today, on the 10th day of the Muslim lunar month of Muharram, the most holy day in the Shi'ite calendar. But Iraqi security forces were tipped off about their presence, Gulal said.
Iraqi security forces struck at dawn but were overwhelmed by the militants, who had dug trenches . At least two Iraqi soldiers were killed in the initial fighting, a security official in Baghdad said.
Iraqi forces then called in US air support and the Scorpion Brigades, an Iraqi quick-reaction force based in a neighboring province.
Helicopters arrived, but after one crashed about 1:30 p.m., they were replaced by higher-flying jets, as American Humvees and armored vehicles rolled into the area.
Three more Iraqi soldiers were killed, as were at least 250 of the fighters, according to several Iraqi officials. Those numbers could not be independently confirmed. By 4 p.m., the tide of the battle had shifted, but US forces continued bombing into the night in an attempt to stamp out remnants of the militants, Iraqi officials and witnesses said.
Two US soldiers and a Marine were killed in three separate attacks around Iraq on Saturday, the US military said yesterday. The deaths brought the number of US military personnel killed in Iraq since the US-led invasion in 2003 to 3,080, according to icasualties.org.
Violence began early yesterday morning and continued throughout the day in several Iraqi cities, including Kirkuk, where bombings killed 14 people, and Babil, where mortars killed 10, and five bodies were found in the Tigris River. A suspected Ba'ath Party loyalist was assassinated in the southern city of Kut, and in the western city of Fallujah, a car bomb killed two and injured four.
Killers in Baghdad targeted both Sunnis and Muslims. In a Sunni neighborhood in western Baghdad, mortars hit a girl's secondary school, killing five students and wounding 21 others.
In another western neighborhood, explosives hidden in a wooden cart killed four and injured 18, while an industry ministry adviser and his daughter were gunned down nearby .
In a Shi'ite neighborhood on the east side of the Tigris , a bomb exploded on a bus, killing one and injuring five others.
Attackers elsewhere in the capital gunned down a bank clerk in a car lot near her house, and at least 54 bodies were found in various Baghdad neighborhoods .