BAGHDAD, Iraq - A suicide bomber detonated hidden explosives on a small bus in Baghdad today, killing at least five people, and two American soldiers died in separate attacks, authorities said.

One of the Americans died in a roadside bombing between the cities of Fallujah and Ramadi, while the other was killed by small arms fire in Ramadi, the U.S. military said.

The deaths raised to 1,912 the number of U.S. troops killed in Iraq since the war began in 2003, according to an Associated Press count.

President Bush, briefed at the Pentagon on Thursday, acknowledged the loss of American lives and said, "We'll honor their sacrifice by completing the mission and winning the war on terrorism."

He added that withdrawing American forces from Iraq would make the world more dangerous and allow terrorists "to claim an historic victory over the United States."

In Baghdad, the suicide bomber struck while on the public bus in a bustling, open-air bus terminal, killing five people and wounding eight, police said.

Also in Baghdad, gunmen killed two members of the commission charged with ensuring former members of Saddam Hussein's Baathist regime were banned from the Iraqi hierarchy, police said.