Baghdad, Iraq ? A roadside bomb killed seven U.S. soldiers in northwest Baghdad, and two Marines were killed in western Iraq on Thursday, the deadliest day for American forces since a suicide attack on a U.S. base last month.

The bombing came as Iraq extended a state of emergency by 30 days to battle militants whose attacks have surged ahead of this month’s elections. The prime minister warned the number of assaults would only rise as voting day draws closer.

Just three weeks before the Jan. 30 elections, the commander of U.S. ground forces in Iraq acknowledged that security was poor in four of 18 Iraqi provinces. But Lt. Gen. Thomas Metz said at a briefing in the capital that delaying the vote would only increase the danger.

“I can’t guarantee that every person in Iraq that wants to vote, goes to a polling booth and can do that safely,” Metz said. “We’re going to do everything possible to create that condition for them, but we are fighting an enemy who cares less who he kills, when he kills and how he kills. A delay in the elections just gives the thugs and terrorists more time to continue their intimidation, their cruelty, their brutal murders of innocent people.”

The soldiers with Task Force Baghdad were on patrol Thursday evening when their Bradley fighting vehicle hit the explosive, the military said in a statement.

No other details were immediately available about the latest attack. But Iraq’s insurgents have frequently targeted American troops with crude explosives planted in roads and detonated remotely.

The two other U.S. Marines killed in action Thursday were members of the 1st Marine Expeditionary Force and lost their lives in Anbar province, which is home to the volatile city of Fallujah.

Thursday’s toll was the highest for the U.S. military in Iraq since a Dec. 21 suicide bombing at a mess tent in Mosul that killed 22 people, including 14 U.S. soldiers and three American contractors.

The latest deaths brought the number of U.S. troops killed since the beginning of the Iraq war in March 2003 to 1,350, according to an Associated Press count. At least 1,063 died as a result of hostile action.

The military said the names of the troops who died Thursday were being withheld until their families were notified.

As militants continued with the attacks, Iraqi authorities made some grisly discoveries. Police in the southern city of Basra found two charred and beheaded bodies in a house used by election officials. Police also announced they found the bodies of 18 young Shiites killed last month while seeking work at a U.S. base.

The state of emergency, originally announced two months ago, was extended for 30 days, a government statement said. The decree includes a nighttime curfew and gives the government additional power to make arrests.