Updated at 7:38 p.m. EDT
Eight American troops were killed in two separate bomb attacks Tuesday in southern Afghanistan, making October the deadliest month of the war for U.S. forces since the 2001 invasion to oust the Taliban.
In one of the insurgent assaults, seven Americans were killed while patrolling in armored vehicles, U.S. forces spokesman Lt. Col. Todd Vician said. He said an Afghan civilian died in the same attack. The eighth American was killed in a separate bombing elsewhere in the south, also while patrolling in a military vehicle, he said.
The military issued a statement saying the deaths occurred during "multiple, complex" bomb strikes. It said several troops were wounded and evacuated to a nearby medical facility, but gave no other details.
"Complex" attacks are a tactic insurgents have used before to deadly effect, reports CBS News correspondent Mandy Clark. The American military convoy traveling northwest of Kandahar, was hit by a powerful roadside bomb. Insurgents then attacked with small arms fire amid the confusion.
Capt. Adam Weece, a spokesman for American forces in the south, said both attacks occurred in Kandahar province. In Washington, a U.S. defense official said at least one was followed by an intense firefight with insurgents who attacked after an initial bomb went off. The official spoke on condition of anonymity because he wasn't authorized to release the information.
CBSNews.com Special Report: Afghanistan
Today's deaths come on the heels of - 14 Americans died in two separate helicopter crashes. Four died after two marine helicopters collided in mid-air. Another 10 Americans died when a Chinook helicopter went down after picking up soldiers from a pre-dawn raid.
This recent spate of violence - 22 deaths in 48 hours - comes during a time of year when fighting in Afghanistan usually slows down as falling snow closes off mountain passes, Clark reports.
But an upcoming runoff election has the Taliban ignoring the harsh cold season. They've promised more violence ahead of the Nov. 7 vote as the people of Afghanistan await President Obama's decision to send in more troops.
The deaths bring to 55 the total number of American troops killed in October in Afghanistan. The previous high occurred in August, when 51 U.S. soldiers died and the troubled nation held the first round of its presidential election amid a wave of Taliban insurgent attacks.
"If he's going to believe that Afghanistan is a mission that's worthwhile he's going to have to accept that there could be days like this," said the Brookings Institute's Jeremy Shapiro.
The deadliest month of the Iraq conflict for U.S. forces was November 2004, when 137 Americans were killed during the assault to clear insurgents from the city of Fallujah.
"A loss like this is extremely difficult for the families as well as for those who served alongside these brave service members," said Navy Capt. Jane Campbell, a military spokeswoman. "Our thoughts and prayers are with the families and friends who mourn their loss."
The loss of life followed one of the worst days of the war for U.S. forces in Afghanistan since they launched air strikes in 2001 to oust the Taliban from power.
On Monday, a U.S. military helicopter crashed returning from the scene of a firefight with suspected Taliban drug traffickers in western Afghanistan, killing 10 Americans including three DEA agents. In a separate crash the same day, four more U.S. troops were killed when two helicopters collided over southern Afghanistan.
U.S. military officials insisted neither crash was the result of hostile fire, although the Taliban in the western province of Badghis. The U.S. did not say where in western Afghanistan its helicopter went down, and no other aircraft were reported missing.
Those casualties marked the Drug Enforcement Administration's first deaths since it began operations here in 2005. Afghanistan is the world's largest producer of opium - the raw ingredient in heroin - and the illicit drug trade is a major source of funding for insurgent groups.
The increased violence comes as President Barack Obama weighs whether to send tens of thousands more troops to the country. On Monday, Mr. Obama pledged not to on what to do next in the troubled war.
"I won't risk your lives unless it is absolutely necessary," Mr. Obama told service men and women at Naval Air Station Jacksonville. He promised a "clear mission" with defined goals and the equipment needed to get the job done.
Further complicating Mr. Obama's decision is the political uncertainty surrounding Afghanistan. The Afghan government is between President Hamid Karzai and challenger Abdullah Abdullah. The runoff comes after complaints by international monitors of fraudulent voting in the first election.
© 2009 CBS Interactive Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.