Two suicide bombers have targeted a Shia mosque in Baghdad, killing 29 people and wounding 55 more.
One of the attackers detonated his device up at a nearby checkpoint, while the other slipped inside during prayers.
Two police officers said the first bomber detonated his explosives in an apparent attempt to distract the authorities.
Amid the commotion, a second bomber slipped past concrete blast walls and into the mosque, where he set off his device while worshippers were performing midday prayers.
Most of the casualties were students from the nearby Imam al-Sadiq University for Islamic Studies.
Police officials said the university's Shia students usually perform their midday prayers in the mosque that was hit.
After the blasts, security forces quickly sealed off the area around the simple, unadorned mosque.
Violence has surged in Iraq in recent months, along with sectarian and political tensions.
There was no immediate claim of responsibility, but suicide bombings and attacks against Shia worshippers are frequently the work of al-Qaeda's Iraq arm.