More than 60 people have been killed in a wave of car bombs across the Iraqi capital security and medical sources said.
The deadliest blast took place in the Bayaa district, where a car bomb exploded, killing 23 people.
Many of the people killed were young people playing billiards.
Elsewhere, gunmen have occupied a university in Iraq's western Anbar province, taking hundreds of students and their professors hostage.
This the third attack this week by militants who overran parts of two other cities.
After fighting their way past guards overnight, the gunmen broke into Anbar University in the provincial capital Ramadi.
Parts of Ramadi have been held by anti-government tribesmen and insurgents since the start of the year.
Security forces surrounded the university in Ramadi and exchanged fire with the militants.
The militants had planted bombs behind them and were patrolling the rooftops with sniper rifles.