A homicide bomber probably caused the blast that killed 22 people, including 14 American soldiers, at an American base in Mosul (search) Tuesday, a preliminary investigative report has found.
"Evidence found at the site includes components normally associated with improvised explosive devices," the report, released late Wednesday by the U.S. military in Baghdad, states. "There was no physical evidence of a rocket, mortar, or other type of indirect-fire weapon."
Gen. Richard Myers (search), chairman of the Joint Chiefs of Staff, earlier told reporters at the Pentagon of the investigation's findings.
"At this point it looks like it was an improvised explosive device worn by an attacker," Myers said.
If so, that would mean a terrorist, obviously in some sort of disguise, was able to get onto the base and move freely into a packed dining area at lunchtime.
Initial reports said a 122-mm rocket ripped through the dining tent. But a radical Sunni Muslim group, the Ansar al-Sunnah A (search)rmy, claimed responsibility for the attack and called it a "martyrdom operation" — a reference to a homicide bomber.
The Ansar al-Sunnah Army is believed to be a fundamentalist group that wants to turn Iraq into an Islamic state like that set up in Afghanistan by the former Taliban regime. The group has claimed responsibility for the execution of 12 Nepalese hostages as well as recent attacks in Mosul.
The attack on the Forward Operating Base Marez in Mosul, some 225 miles north of Baghdad, wounded 69 people. Most of the injured flew on an Air Force C-141 transport plane to Ramstein Air Base in Germany on Wednesday for treatment at nearby Landstuhl Regional Medical Center.
Officials first said Wednesday that of the 22 dead, 14 were U.S. military personnel, four were American civilian contractors, three were Iraqi National Guard members and one remained unidentified.
In Wednesday's investigative report, one person's status was changed from civilian contractor to military service member.
The final, unidentified person could be the key to conclusively knowing what caused the explosion.
"It's not inconceivable that a suicide bomber of some sort, posing as a military guy, got in that tent," said Marine Lt. Col. Bill Cowan, a FOX News military analyst.
The explosive was apparently packed with pellets the size of BBs that ripped across the tent, said Brig. Gen. Carter F. Ham, commander of Task Force Olympia.
Mortars and rockets produce shrapnel, but are usually not packed with pellets, which are more often found in roadside bombs or explosive vests worn by homicide bombers.
The blast came as the military was building a reinforced, bunker-like dining area at the camp to increase protection against mortar and rocket attacks, officials said. The new facility was due to be completed in February.
Lt. Gen. Thomas Metz, one of the American commanders in Iraq, said on FOX News' "FOX & Friends" that U.S. troops would not be deterred.
"The message I would give you today is one of resolve. We aren't going to be intimidated by the thugs," Metz said.
Metz said the "fingerprints" on the attack belonged to former members of Saddam Hussein's regime.
"We think in Mosul those forces have come together to fight the coalition and intimidate the citizens of Mosul and certainly the Iraqi security forces," he said.
Sgt. Kyle Wright of Richlands, Va., recovering from wounds to his leg and back, said he was in the tent about to take a bite of chocolate cake when he was blown into the air.
"When I came to, I looked up and saw open sky," Wright, a member of the 276th Engineer Battalion, told Jeremy Redmon, an embedded reporter from the Richmond (Va.) Times-Dispatch.
Defense contractor Halliburton Co. said four of its employees were killed in the attack. It had initially said three subcontractors were also killed, but it later reported that they had survived. It did not give the nationalities of the dead.
Sixteen other Halliburton workers, including 12 subcontractors, were seriously injured in the blast, the company said.
At Fort Lewis in Washington, home base for many of those stationed at Forward Operating Base Marez, family members waited for word Wednesday on the fate of their loved ones.
Empty Streets in Mosul
U.S. troops backed by armored vehicles swept through virtually empty streets in Mosul Wednesday amid an undeclared curfew in Iraq's third-largest city.
An Associated Press reporter saw almost no cars or people on the streets and most schools in the city were closed. Even traffic policemen were not at major intersections.
U.S. forces blocked the five bridges over the Tigris River that link the western and eastern sectors of the city. Hundreds of troops spread out across several neighborhoods, conducting sweeps in eastern districts backed by Bradley fighting vehicles and armored Humvees.
The AP reporter saw helicopter gunships hovering overhead and jets flying high above the city.
Mosul was relatively peaceful after Saddam Hussein's regime fell in April 2003. But it has become a hotspot for insurgent violence ever since U.S.-Iraqi forces took the main guerrilla stronghold of Fallujah last month.
Tuesday's attack was the latest in a week of deadly strikes across Iraq that highlighted the growing power of the insurgents in the run-up to the Jan. 30 national elections.
Some in Mosul showed little sympathy for the dead Americans, particularly among the city's Sunni Arab majority. The city also is home to a large number of Kurds, whose two main political parties are U.S. allies.
"When occupiers come to any country [they] find resistance. And this is within Iraqi resistance," Sattar Jabbar said of the attack.
"I prefer that American troops leave the country and go out of cities so that Iraq will be safer and we run its affairs," said Jamal Mahmoud, a trade-union official. "I wish that 2,000 U.S. soldiers were killed, not 20."
Mosul was the scene of the deadliest single incident for U.S. troops in Iraq. On Nov. 15, 2003, two Black Hawk helicopters collided over the city, killing 17 soldiers and injuring five.
In other developments Wednesday:
— Poland's Prime Minister Marek Belka and Defense Minister Jerzy Szmajdzinski toured Camp Echo in Diwaniyah, the new headquarters for the Polish-led international security force in central Iraq, as part of a Christmas visit to the roughly 2,400 Polish troops in Iraq.
— Four Iraqi civilians from one family were killed, and three others wounded, when U.S. soldiers opened fire on their car in the Abu Ghraib area just west of Baghdad, said Akram al-Zaobaie, a doctor in the local hospital. The soldier started firing after a bomb hit a U.S. convoy, he said.
— Iraqi security forces stormed a house in the Shiite Muslim holy city of Najaf in a shootout that killed one guerrilla and a policeman. The raid came after 54 people were killed and 142 injured in a car bombing Sunday in Najaf's city center.
FOX News' Steve Harrigan, Dan Springer, Bret Baier, Ian McCaleb and The Associated Press contributed to this report.