Militants, including two suicide bombers, attacked a town north of Baghdad that has resisted jihadists, killing 18 people on Monday, police and a doctor said.
A first suicide bomber blew up a vehicle packed with explosives to breach a barrier in a southern neighbourhood of Dhuluiyah, which the second bomber then penetrated, the sources said.
Security forces and allied tribesmen then clashed with the militants in the Jubur neighbourhood.
Dhuluiyah was previously overrun by militants but local tribes drove them out, and Jubur has put up fierce resistance to renewed attempts by the militants to take the town.
More than 50 people were wounded in Monday's violence, the sources said.
There was no immediate claim for the attack, but suicide bombings are almost exclusively carried out by Sunni extremist groups, including the jihadist Islamic State.