BAGHDAD, Iraq— At least 78 people were killed and more than 150 wounded today after two nearly simultaneous bombs struck a predominantly Shiite commercial area in central Baghdad in the deadliest attack in two months, officials said.

The first blast occurred shortly after noon when a bomb left in a bag placed among the stalls of vendors peddling DVDs and secondhand clothes exploded in the Bab al-Sharqi area between Tayaran and Tahrir squares.

It was followed almost immediately by a parked car bomb just feet away. A suicide bomber killed at least 63 people in the same area last month.

Deputy Health Minister Hakim al-Zamili said at least 78 people were killed and 156 were wounded.

The explosions left body parts strewn on the bloodstained pavement as black smoke rose into the sky. Iraqi police sealed off the area as ambulances rushed to the scene to evacuate the victims.

The bombings were a further sign of what appears to be a renewed campaign of Sunni insurgent violence against Shiite targets. Last week, 142 Iraqis were killed or found dead on Tuesday alone, including 65 students at a leading Baghdad university who died in twin car bombings.

Today's death toll made it the single most deadly attack against civilians in Iraq since Nov. 23, when a series of car bombs and mortar attacks by suspected al-Qaida in Iraq fighters in Baghdad's Sadr City Shiite slum killed at least 215 people.

Hours earlier today, gunmen killed a female teacher as she was on her way to work at a girls' school in the mainly Sunni area of Khadra in western Baghdad, police said, adding that the teacher's driver was wounded in the drive-by shooting.

Two U.S. Marines were killed Sunday in separate attacks in the Anbar province, an insurgent stronghold west of Baghdad, the military said. The deaths came a day after 25 U.S. troops were killed Saturday in the third-deadliest day since the war started in March 2003 — eclipsed only by the one-day toll 37 U.S. fatalities on Jan. 26, 2005, and 28 on the third day of the U.S. invasion.

The heaviest tolls on Saturday came from a Black Hawk helicopter crash in which 12 U.S. soldiers were killed northeast of Baghdad as well as an attack on a provincial government building in the Shiite holy city of Karbala that left five U.S. troops dead.

The violence underscores the challenges faced by U.S. and Iraqi forces as they seek to rein in Sunni insurgents and Shiite militias that have made the capital and surrounding areas a battleground.

Meanwhile, two government officials on Sunday said Iraq's prime minister dropped his protection of an anti-American cleric's militia after being convinced by U.S. intelligence that the group was infiltrated by death squads.