BAGHDAD, Iraq -- The number of U.S. deaths in Iraq is soaring, with more than 20 American troops being killed this weekend.

Militia fighters attacked a provincial headquarters in the Shiite holy city of Karbala, killing five American soldiers Saturday night, the U.S. military reported.

The statement said "an illegally armed militia group" attacked the building with grenades, small arms and "indirect fire," which usually means mortars or rockets.

"A meeting was taking place at the time of the attack to ensure the security of Shiite pilgrims participating in the Ashoura commemorations," said Brig. Gen. Vincent K. Brooks, deputy commander for Multi-National Division-Baghdad.

The 10-day Ashoura marks the death of one of Shiite Islam's most sacred saints, Imam Hussein, grandson of the prophet Muhammad, and thousands of pilgrims are flocking to Karbala for the festivities.

Earlier Saturday, the U.S. military said 13 people were killed in the crash of a U.S. helicopter in Iraq.

A statement said the helicopter went down northeast of Baghdad, killing all servicemembers aboard. It said coalition forces have secured the site.

The chopper may have been having technical problems. That's what a military spokesman has told an Arab news agency. He said the aircraft was a Blackhawk helicopter.

The crash is under investigation, as officials still don't know the exact cause.

It happened in a violent area where U.S. and Iraqi forces have been battling Sunni insurgents and Shiite militia forces around the city of Baqouba for months.

Also this weekend, the U.S. military said an American soldier was killed by a roadside bomb in the capital Saturday. Two American troops were killed in operations outside the capital Friday.

Iraqi Raid

A raid by elite Iraqi police forces dropped off by U.S. helicopter targeted an al-Qaida-linked Sunni militant group in Baghdad. The Interior Ministry said 15 insurgents were killed and five captured.

A spokesman said the quick-reaction Iraqi force, backed by gunfire from the helicopters, met fierce resistance from the members of the militant group who were hiding in two abandoned houses in the Sunni insurgent stronghold of Dora in southern Baghdad.

The operation targeted the militant group known as the Omar Brigade, which is believed to be behind a series of kidnappings and killings aimed at driving Shiites from the neighborhood.

Bush Talks Over War Plans With Top Aides

President George W. Bush has been discussing the Iraq war and other matters with top deputies who've just returned from the Middle East.

He met at the White House Saturday with Secretary of State Condoleezza Rice and Defense Secretary Robert Gates to hear details of their recent trips.

Rice is just back from the Middle East. And Gates returned to Washington Saturday after a whirlwind tour that began last weekend in London and ended Friday in southern Iraq. In between he visited NATO headquarters in Brussels, Belgium, met with troops and officials in Afghanistan and made stops in Saudi Arabia, Bahrain and Qatar.

After their meeting, Bush left for Camp David, accompanied by Rice, national security adviser Stephen Hadley and chief of staff Joshua Bolten.

Bush Taken To Task

Montana's Democratic governor said Bush is wrong on Iraq. Brian Schweitzer said "outsiders" won't be able to fix the situation there unless the "Iraqi people want security and freedom at least as much as us."

In the weekly Democratic radio address, Schweitzer also said that the president has also failed to recognize the importance of energy independence.

He argued that American energy independence is the only way to ensure the country doesn't have to continue fighting wars in the Middle East.

Schweitzer said the U.S. uses more than 6 billion barrels of oil a year, while producing less than 3 billion. He said the rest comes from "some of the world's worst dictators."