Bombs struck a double-decker bus and a taxi in eastern Baghdad on Monday, killing four people and wounding 12 others, authorities said.

Iraqi police and hospital officials said the bus was carrying employees of Iraq's Housing Ministry through the Shiite-dominated neighborhood of Mashtal when it was hit by a roadside bomb.

Two people died in that attack, said the officials, who spoke on condition of anonymity because they were not authorized to disclose the information. Seven people were wounded and brought to Baghdad's Kindi hospital.

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The U.S. military confirmed that seven people were wounded, but said only one was killed. Conflicting casualty tolls are common in Iraq.

Iraqi police arrested one man at the site of the blast, said Lt. Col. Steven Stover, a military spokesman. He blamed Shiite extremists for the attack.

"It's a heinous act, especially considering they are targeting innocent civilians," Stover said.

In a separate attack, a bomb placed under a taxi exploded at Maysaloun Square in east Baghdad, police said. Police and health officials said two people were killed in the blast and two others were injured.

The attacks occurred as Iraqi politicians are weighing whether to support a security agreement with the U.S. The pact would keep American troops in the country for three more years to help Iraqi forces prepare for full responsibility of the country.

A draft agreement produced after months of intensive negotiations has drawn criticism from several political groups, raising concern that it could fail to win parliamentary approval by Dec. 31 when the U.N. mandate expires.

The Iraqi Cabinet will probably discuss the draft Tuesday but is not expected to vote on it, said Sami al-Askari, an aide to Prime Minister Nouri al-Maliki.

If the Cabinet votes to approve the draft, it will be sent to parliament for a final decision.

The U.S. military, meanwhile, said in a statement that a U.S. Marine died Sunday in a non-combat incident at Asad Air Base in the west of Iraq. It provided no further details but said the incident was being investigated.

The Marine's name was not released pending notification of kin. At least 4,186 members of the U.S. military have died in the Iraq war since it began in March 2003, according to an Associated Press count.

Also Monday, an Iraqi policeman was arrested for allegedly using police vehicles to smuggle weapons to Baghdad. Iraqi forces captured the man, acting on a warrant from the Interior Ministry, the U.S. military said in a statement.