U.S. military forces experienced their deadliest day in Iraq since the beginning of the 2003 war as 31 personnel died in a helicopter crash and another six died in insurgent attacks.
Lt. Gen. John Sattler, commander of the 1st Marine Expeditionary Force (search) in Iraq, said 30 Marines and one U.S. sailor were killed in the crash of a Marine helicopter that was transporting troops in the deser of western Iraq.
Army Gen. John Abizaid (search), chief of U.S. Central Command, said the helicopter was on a mission in support of the upcoming national election. The crash occurred in severe weather, but its cause was still under investigation, he said. An Accuweather map of Iraq showed sandstorms near the Jordanian border where the crash took place.
The CH-53E Super Stallion (search) was carrying personnel from the 1st Marine Division when it went down about 1:20 a.m. near the town of Rutbah, about 220 miles west of Baghdad, the military said in a statement.
President Bush was asked about the fatal crash during a White House news conference.
"Listen, the story today is going to be very discouraging to the American people. I understand that. We value life and we weep and mourn when soldiers lose their life," he said. "But it is the long-term objective that is vital, and that is to spread freedom."
He said he didn't have details on the crash. "I know that it's being investigated by the Defense Department. Obviously, any time we lose life, it is a sad moment," he said.
Asked about reports that the crash may have been weather-related, Bush said, "I've heard rumors, but let's wait for the facts."
A Pentagon source said the helicopter is normally configured to carry 37 passengers, but can take up to 55.
A search and rescue team has reached the site and an investigation into what caused the crash is underway, the military said.
In Iraq's Anbar province, four U.S. Marines were killed in fighting, the military said in a statement.
The statement gave no further details, but WABC reporter Jim Dolan, who was embedded with the troops who were attacked, said the deaths came when insurgents ambushed a Marine convoy leaving the town of Haditha, west of Baghdad, hitting a vehicle with a rocket-propelled grenade.
Also Wednesday, insurgents attacked a U.S. Army patrol near the northern town of Duluiyah, killing one soldier and wounding two others, and in the Baghdad area a roadside bomb killed another soldier and wounded two others, the U.S. command said..
The day's deaths brought to at least 1,409 the number of members of the U.S. military who have died in Iraq, according to an Associated Press count.
The previous single deadliest incident for U.S. troops was also a helicopter crash: In November 2004, two Black Hawk helicopters collided while trying to avoid ground fire, killing 17 servicemembers. Earlier that month, a Chinook transport helicopter was shot down by shoulder-fired anti-aircraft missile near Fallujah, killing 16 American soldiers and wounding 26.
The U.S. military has lost at least 33 helicopters since the March 2003 start of the Iraq conflict, according to a study by the Brookings Institution (search). At least 20 of them were brought down by hostile fire, the institution said.
The deadliest single incident involving U.S. troops until Wednesday took place on Nov. 15, 2003, when two Black Hawk helicopters crashed in Mosul after colliding while trying to avoid ground fire, killing 17 U.S. soldiers and wounding five.
Earlier that same month, on Nov. 2, 2003, a Chinook transport helicopter was shot down by shoulder-fired anti-aircraft missile near Fallujah, killing 16 American soldiers and wounding 26.
Last month, a homicide bomb exploded at a mess tent in a base near Mosul, killing 22 people including 14 U.S. soldiers and three American contractors.
FOX News' Bret Baier and The Associated Press contributed to this report.