The violence came as Iraqi lawmakers prepared for a vote Wednesday on a security pact with the United States that would enable American forces to stay in Iraq for up to three more years under strict Iraqi oversight.
The Interior Ministry said it was stepping up security in the capital in response to the attacks. Additional measures included putting more undercover agents on the streets, it said in a statement.
The first attack occurred shortly before 8 a.m. when a bomb attached to a bus used by the Trade Ministry to ferry employees to work exploded in eastern Baghdad, police and hospital officials said on condition of anonymity because they were not authorized to speak to the media.
Thirteen ministry employees were killed and three were wounded, according to an official with the state-owned Iraqi shopping centers company who also spoke on condition of anonymity. The company is part of the Trade Ministry.
The rush-hour attack occurred in a Shiite area and the injured were taken to Kindi and Ibn al-Nafis hospitals in Baghdad.
An official at Kindi hospital's emergency wing and another official at Ibn al-Nafis said eight women were among the 13 people killed. Most of the bodies were severely burned, making identification difficult.
The U.S. military said 14 people were killed and four were injured in the 7:20 a.m. bombing of the minibus. It said American soldiers assisted Iraqi police in securing the area and treating casualties.
About 45 minutes later, a female suicide bomber blew herself up as she stood in line to be searched at a checkpoint near the Green Zone in central Baghdad, killing seven people and wounding 13, according to an Interior Ministry official who declined to give his name.
Ahmed al-Sayyid, 23, was waiting in line with friends at the entrance to the Green Zone when a woman in black robes approached the checkpoint.
"Suddenly, she blew herself up about 50 meters from where I was standing. I was horrified and I ran away. But seconds later, I returned to the explosion site, which was filled with smoke, and I could see some wounded people and pieces of flesh," al-Sayyid said.
Iraq's intelligence service said the bomber had targeted the checkpoint where its workers enter the Green Zone to go to work at the agency's headquarters, which is inside the fortified area. The service said female employees, including a pregnant woman, were killed and some of its guards were injured.
Kindi hospital said two women were among those killed in the blast.
The U.S. military said the bombing near the Green Zone occurred between 8:30 a.m. and 9 a.m. and killed two Iraqi army members and three civilians. One civilian was injured, it said.
The Green Zone houses the U.S. Embassy and the Iraqi government headquarters.
In a third attack, a roadside bomb targeted a police patrol around 10:30 a.m. near Technology University in eastern Baghdad, killing two civilians and wounding four other people, an Iraqi police officer and an official at Ibn al-Nafis hospital said on condition of anonymity. Two police officers were among the injured.
In Baqouba, 35 miles (60 kilometers) northeast of Baghdad, a policeman was killed when a roadside bomb blew up near his car, police said.
