BAGHDAD - Bombings and shootings killed more than 30 people across Iraq yesterday, including high school students on their way to final exams, part of a new round of violence ahead of next week's deadline for U.S. troops to withdraw from urban areas.

The attacks pushed the three-day Iraqi death toll over 100, shattering a recent lull and adding fresh doubt to the ability of government forces to protect people without U.S. soldiers by their sides. American combat troops have already begun moving from inner-city outposts to large bases outside Baghdad and other cities.

Overall levels of violence remain low, but Iraqi officials have warned that extremists will likely carry out more attacks to erode public confidence in the government as the Americans pull out of cities by next Tuesday, the first step toward a full withdrawal from the country by the end of 2011.

Many Iraqis support the withdrawal timeline, outlined in a security pact that took effect this year. But others fear extremists will regroup without the visible presence of U.S. soldiers.

"There aren't enough Iraqi army and police, and they're ill-equipped to confront the terrorists," said Abdul-Salam Mohammed, 33, a car dealer in the former insurgent stronghold of Baqubah. "The pullout is not in our interest at this moment because we are still in the recovery phase and not yet cured."

Prime Minister Nouri al-Maliki acknowledged over the weekend that more violence was likely but said Iraqi forces were ready and called on Iraqis to remain steadfast.

Yesterday's violence mainly struck Shiite neighborhoods in the Baghdad area, starting with a roadside bombing of a minibus carrying high school students from Sadr City to their final exams.

Police said the attack killed at least three students and wounded 13 people. The bus was pockmarked with shrapnel, with blood-soaked notebooks and ID cards left on the seats and the floor.

A bomb planted under a car also exploded on a road leading to a checkpoint that controls access to a bridge into Baghdad's central Green Zone, killing at least five and wounding 20, according to police and hospital officials. A roadside bomb later targeted a police patrol in eastern Baghdad, killing three

Hours later, a parked motorcycle loaded with explosives blew up in an open-air public market in an impoverished, predominantly Shiite area northeast of Baghdad, killing five people and wounding 22, police and hospital officials said.

Seven people were killed when a suicide car bomber targeted the mayor's offices in Abu Ghraib, a predominantly Sunni district west of Baghdad. The car exploded before reaching the government building, damaging a nearby U.S. vehicle that was providing security for a meeting, a U.S. military spokesman, Maj. David Shoupe, said.

Gunmen also killed at least seven people in separate attacks in the northern city of Mosul, including a woman and four Iraqi security forces, police reports said.

North of the capital and close to the Iranian border, a roadside bomb struck an Iraqi army patrol, killing three soldiers, according to the security headquarters in Diyala province.

U.S. commanders acknowledge that the attacks are hard to stop but note that retaliatory violence has not come anywhere near the level of sectarian bloodshed that brought Iraq to the brink of civil war in 2006.