The deadly attack, which took place in the town of Muqdadiyah in the Diyala Province, also left an unknown number of people injured.
A security source in Diyala said more than 10 other people were injured in the attack which targeted a funeral ceremony in Muqdadiyah around noon local time.
The state-run agency WAP said the attacker hit a gathering of people inside a mosque in Fereshteh district, located east of Muqdadiyah and 40 kilometers northeast of the provincial capital of Baqubah.
The governor of Muqdadiyah, Adnan al-Tamimi, said an investigation has been launched into the incident. He said security forces swiftly reached the scene of the attack while ambulances carried the victims to the hospitals.
No group or organization has claimed the deadly attack although the government in Baghdad blames the Takfiri group Daesh for such attacks. The militant group, which controls areas in west and north of Iraq since June 2014, has suffered major defeats over the past months at the hands of Iraqi military forces and allied volunteer fighters, Press TV reported.
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