BAGHDAD, Iraq – Twin bombings Monday tore through stalls of vendors selling second-hand clothes and DVDs in a busy Baghdad market catering to Shiite Muslims during a religious festival.

A market also was attacked north of the capital, and police said as many as 100 people died in the renewed campaign blamed on Sunni Muslim insurgents.

The U.S. military also reported the deaths Sunday of two Marines, raising the two-day death toll to 27 in a particularly bloody weekend for American forces in Iraq.

A roadside bomb killed a U.S. soldier and wounded four others Monday in northern Iraq, it said.

Monday’s first blast, a parked car bomb, hit shortly after noon in the Bab al-Sharqi market between Tayaran and Tahrir squares – one of the busiest parts of Baghdad. Seconds later, a suicide car bomber drove into the crowd.

Police estimated that each car was loaded with nearly 220 pounds of explosives.

Deputy Health Minister Hakim al-Zamili said at least 78 people were killed and 156 were wounded, making it the deadliest attack in two months. Figures provided by police and hospital officials showed that as many as 88 people were killed.

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

Survivors were taken to nearby al-Kindi Hospital where emergency personnel worked feverishly over the bloodied and badly wounded.

Bodies covered in blue and white cloth littered the outdoor courtyard at the hospital. Family members and friends were at the side of the dead, screaming in grief and crying out oaths.

A suicide bomber killed at least 63 people in the same area last month.

Prime Minister Nouri al-Maliki, a Shiite, denounced the attack.

“We condemn this crime and we promise that the security forces will pursue all those involved in this crime and bring them to justice,” he said in a statement.

Hours later, a bomb followed by a mortar attack struck a market in the predominantly Shiite town of Khalis, 50 miles north of Baghdad, killing at least 12 people and wounding 29, police said.

The twin bombing in Baghdad was the single deadliest attack against civilians in Iraq since Nov. 23, when suspected al-Qaida in Iraq fighters attacked Baghdad’s Sadr City Shiite slum with a series of car bombs and mortars that struck in quick succession, killing at least 215 people.

In other violence, gunmen killed a 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.