The first suicide bomber detonated his vehicle near a group of policemen outside the Nahda bus station in central Baghdad at about 8 a.m. local time, the U.S. military said.
A second car exploded in the open-air station's parking lot near buses that carry passengers to Amarah and Basra, Shiite-dominated cities in southern Iraq, police Capt. Nabil Abdul-Qader said, according to the Associated Press.
A third suicide bomber exploded his vehicle about 30 minutes later near the Kindi Hospital, where many of the wounded from the first two explosions were taken for treatment. It was unclear if the hospital was the target of the blast.
"We heard an explosion in the garage, we went there and ran towards the buses for Kut, Basra and Amarah," witness Ahmed Jabur told Reuters at the scene.
While suicide attacks continue with relative regularity in Iraq, the triple attacks were the most deadly in weeks. Abdul-Qader said 43 people were killed and 85 wounded in Wednesday's blasts.
Four suspects were being detained at the bus station on suspicion of being involved in the attacks and were being questioned, the Transportation Ministry said, the AP reported.
The violence came amid attempts by Iraqi politicians to complete a draft constitution after they missed a Monday deadline to finish it. Parliament voted to extend the deadline until Aug. 22.
The largest Sunni Arab political party criticized the committee shaping the constitution, calling it "biased and chaotic" and accusing it of trying to divert discussions away from Sunni objections over federalism, which the minority fears would split the country, reported the AP.
Along with which regions should have autonomy, control over oil and other resources continues to be a sticking point.