A string of bombings killed at least 18 people across Iraq on Monday, shattering a relative lull in violence during the celebration that marks the end of the Islamic holy month of Ramadan.

The blasts primarily targeted Iraqi security forces, which have been the focal point of insurgent attacks since U.S. troops pulled out of Iraq's cities at the end of June. The uptick in violence also comes as the country's shops and schools reopened after the Eid holiday that follows the end of the Muslim holy month.

The deadliest attack Monday occurred in Ramadi, about 70 miles west of Baghdad, when a suicide bomber slammed a tanker truck packed with explosives into a police post, killing at least seven people and wounding 16 more, a security official said.

The official spoke on condition of anonymity because he was not authorized to release the information.

Witnesses said the truck exploded near the front gate of the post, which is home to one of seven police battalions in the area, setting cars and trucks on the base on fire.

"It is like an earthquake occurred in this place," a police official said, speaking on condition of anonymity because he was not authorized to speak to the media.

He said the blast caused a fireball powerful enough to throw cars into the air and overturn trucks.

Ramadi is the capital of Anbar province, a former Sunni insurgent stronghold in the vast stretch of land west of Baghdad to the Jordanian border. The region has been relatively stable since Sunni fighters turned against Al Qaeda in Iraq and joined forces with the U.S. military in 2006 to fight the insurgency. But the province has been shaken in recent weeks by a series of attacks on police and Iraqi army checkpoints.

Despite the dramatic drop in violence nationwide since the fierce sectarian bloodletting that engulfed Iraq in 2006 and 2007, insurgents still regularly target Iraqi security forces across the country.

Three Iraqi soldiers were killed Monday in a double roadside bombing in the predominantly Sunni neighborhood of Ghazaliyah in western Baghdad, a police official said.

Fifteen others, including 11 civilians, were wounded in the attack.

In southern Iraq, a bomb attached to a bus killed at least six people, while in the northern city of Mosul two policemen were killed and two others wounded when a roadside bomb hit their patrol, two security officials said.

The officials all spoke on condition of anonymity because they were not authorized to release the information.

The news came as the U.S. military freed another 35 members of a group linked to the abduction of five British citizens from Iraq's Finance Ministry in 2007, a representative for the faction said.

The prisoner release means nearly 100 members of Asaib Ahl al-Haq, or League of the Righteous, have left U.S. custody since late last week. In total, about 250 have been freed since July as talks intensify over the fate of the sole British hostages believed to be still alive.

An envoy for the militant group, Salam al-Maliki, said the talks also are seeking the release of its leader, Sheikh Qais al-Khazali.

But negotiations are complicated by efforts to seek guarantees to free Peter Moore, the remaining hostage.

"We are trying to free (al-Khazali). His case is postponed for the time being," al-Maliki said.

A group of armed men seized Moore, a computer expert working for a U.S.-based consultancy firm, and his four bodyguards from the Finance Ministry in May 2007. The bodies of at least three of the hostages have been identified, but Moore is believed still be alive.