Five U.S. Marines were killed when a roadside bomb detonated beside their armored vehicle convoy 15 miles from Fallujah, Iraq, and four civilian contractors -- all of whom were U.S. citizens -- were killed in an unrelated attack in Fallujah March 31, coalition officials said.

Despite these attacks, the overall Iraqi area of operations remains relatively stable, and the Coalition Provisional Authority (CPA) continues to make progress in governance, economic development and restoration of essential services, said Brigadier General Mark Kimmitt, the deputy director of operations for the Combined Joint Task Force Seven.

"Over the past week there's been an average of 28 engagements daily against coalition military, five engagements daily against Iraqi security forces, and just under four attacks daily against Iraqi civilians," Kimmitt said during a briefing in Baghdad.

Kimmitt said the four contractors killed in the Fallujah attack were in two vehicles. Television news reports showed the vehicles on fire and showed scenes of the remains being attacked by people in Fallujah. Several insurgents attacked the civilian convoy with hand grenades and small arms fire.

CPA Senior Advisor Dan Senor said at the briefing that those who attacked the civilian convoy are not people the coalition is there to help.

"They are people who have a much different vision for the future of Iraq than the overwhelming majority of Iraqis," Senor said. "They are people who want Iraq to turn back to an era of mass graves, of rape rooms, and torture chambers and chemical attacks. They want to turn back to the era of Saddam Hussein."

Kimmitt said the contractors were working for the CPA in some capacity, but it was not immediately known what their jobs were. He also said elements of the U.S. First Marine Expeditionary Force is responsible for security in the region around Fallujah where the two attacks occurred, and they will restore order to Fallujah.

The Marines who were killed in a separate incident were traveling along a regular supply route when the roadside attack occurred, officials said. The attack occurred in the al-Anbar province near Malahma, about 12-15 miles northwest of Fallujah.

"One isolated incident in a town such as Fallujah ( has not stopped the process of building inside this country," Kimmitt said. "It has not stopped the process of moving on toward passing governance on to the people of Iraq. And it has not stopped the restoration of essential services in this country."

White House spokesman Scott McClellan said that despite these attacks the United States is holding fast to a June 30 deadline for handing over power in Iraq to the transitional Iraqi government. "These are horrific attacks by people who are trying to prevent democracy from moving forward, but democracy is taking root," he said.