According to Tuesday reports, a bomber detonated his charge at a checkpoint located around 100 meters from the mosque in the al-Qahira district of northern Baghdad.
A second bomber blew himself up inside the building minutes after the first explosion.
Furat Faleh, an Iraqi police officer near the incident scene, said the bomber inside the mosque “detonated himself among the worshippers, who were gathering after the call to prayer.”
No group has claimed responsibility for the deadly attacks so far.
There has recently been an upsurge in violence across Iraq, and authorities say Qatar and Saudi Arabia have had a hand in some of the deadly incidents.
On June 16, at least 51 people lost their lives and many others were injured in a series of bomb attacks and a shooting across the violence-hit country.
The United Nations says a total of 1,045 people were killed and nearly 2,400 were injured in violent incidents across Iraq in May.
On Monday, UN Secretary-General Ban Ki-moon’s special representative for Iraq Martin Kobler called on the Iraqi leaders to “sit together” to address the country’s problems, including car bomb attacks throughout Iraq.
“Nothing can justify such despicable and heinous crimes targeting innocent people going about their daily business,” Kobler said.
Iraqi Prime Minister Nouri al-Maliki has said that militant groups and the remnants of the former Ba’athist regime are responsible for the latest wave of violence.