Roadside bombs killed seven American troops in the past two days, U.S. military officials reported, making October the fourth-deadliest month for U.S. forces since the Iraq war began.

In western Iraq, U.S. warplanes struck what a military spokesman called a terrorist safe house. Residents and physicians at area hospitals said about 40 people were killed in the attack, including women and children, in addition to fighters belonging to the insurgent group al Qaeda in Iraq.

In the southern city of Basra, a car bomber crashed into a police car in a crowded shopping and restaurant district at about 8:45 p.m. The resulting fiery blast killed at least 20 people and wounded several dozen others who were celebrating the end of their daily fast for Ramadan, officials said.

Witnesses said Jazaer Street, a popular pedestrian area with ice cream stands and other roadside stalls, was littered with body parts, smashed storefronts and demolished cars.

Six U.S. soldiers died in two incidents Monday, military statements said. Four of them were killed in Yusufiyah, about 12 miles southwest of Baghdad, when their patrol was struck by a roadside bomb. Two soldiers attached to the 29th Brigade Combat Team were killed when their patrol was hit by a roadside bomb outside a U.S. air base near Balad, about 45 miles north of the capital.

In an incident Sunday, a Marine was killed by a roadside bomb near Amiriyah, about 30 miles southwest of Baghdad. Identities of the dead were withheld pending notification of their families.

The fatalities raised the U.S. combat death toll in October to at least 92. The deaths pushed the number of U.S. military fatalities in the 31-month-long war to 2,025, according to an Associated Press count. The only higher monthly tolls were 137 in November 2004, 135 in April 2004 and 106 in January 2005, according to a Washington Post count.

The Pentagon announced Monday that the highest-ranking Army officer killed so far in combat during the Iraq war died Thursday. Col. William W. Wood, 44, of Panama City, Fla., was killed as he responded to a bomb attack and a second bomb exploded. Wood, who was promoted from the rank of lieutenant colonel after his death and was an active-duty officer in the 3rd Infantry Division, was on special assignment commanding the Army National Guard's 1st Battalion, 184th Infantry Regiment, an Army official said.

The leading killer of U.S. troops during October was roadside bombs, known in military parlance as improvised explosive devices, or IEDs. At least 55 U.S. troops were killed by the weapons in October, accounting for about 72 percent of all U.S. fatalities by hostile action during the month.

It was the highest monthly total for roadside bomb deaths since the start of the war; the next highest were 37 in September and 40 in August, according to Iraq Index, a database maintained by the Brookings Institution. The figures underscore the increasing sophistication of IEDs and the difficulty U.S. soldiers are having in detecting them.

The U.S. military said American warplanes bombed "a terrorist safe house" before dawn near Karabilah, a village near the town of Qaim, which is about 200 miles west of Baghdad on the border with Syria. The town lies in the Euphrates River valley, which stretches from the border almost to the Iraqi capital. U.S. military officials say it is a key corridor for the smuggling of foreign fighters and materials from Syria into Iraq.

"A senior al Qaeda cell leader was the target of the strike," a U.S. military spokeswoman said in an e-mail response to questions about the incident. "The timing of the attack and the use of precision-guided munitions is intended to avoid civilian casualties."

Residents and hospital officials from the area reached by telephone disputed key elements of the military version, saying that three houses in Baidah, near the border town of Husaiba, were bombed, and only one was being used by the group al Qaeda in Iraq, led by Abu Musab Zarqawi. Numerous civilians were killed in the raids, they said.

"We saw Zarqawi's group pulling out bodies from under rubble of one of the houses, and they didn't care about the rest," said Khalid Elayan, an ambulance driver.

"Forty people were killed in the bombing, including nine women and children," said Ammar Marsoumi, a physician at Husaiba hospital. Muwaffaq Ani, a doctor in the nearby town of Ana, said his hospital received 17 wounded, including a 4-year-old girl whose mother was killed in the raid.

A doctor at the hospital in Qaim said the death toll included fighters from al Qaeda in Iraq, but that other members of the group took the bodies and did not bring them to the hospital. The doctor spoke on condition of anonymity, citing security concerns.

"We all know this house belonged to Zarqawi's group and was owned by a leader in the group, but the other two houses were for civilians," said Omar Nasir, 32, a taxi driver who said he went to the bombing site. "If the killed were only Zarqawi's men, we would say it is a war and they had the right to do it," he said. "But this time, the Americans killed many Iraqis to get Qaeda fighters."

Staff writer Josh White in Washington contributed to this report.