At least 31 people were killed when ISIL militants opened fire and later blew themselves up in the Iraqi city of Tikrit.
Police and army officers said the attack, which began on Tuesday night, also wounded at least 42 people.
A police lieutenant colonel said three militants shot dead three policemen in Tikrit and then opened fire on civilians, before later blowing themselves up inside homes in the area.
ISIL said seven of its militants carried out the attack.
ISIL seized Tikrit during a lightning offensive that overran large areas north and west of Baghdad in the summer of 2014, but Iraqi forces recaptured it the following year.
Iraqi forces are now battling to retake west Mosul — the country’s last city in which the extremists hold significant ground.
On Wednesday, Iraq’s military urged residents to shelter in their homes in ISIL-held areas of Mosul, where its bid to oust the group has taken a heavy toll on civilians.
Hundreds have been killed or wounded and more than 200,000 have been forced to leave their homes.
The government has encouraged residents not to flee during the fighting — a policy aimed at easing the burden of widespread displacement but which can heighten the risk of injury or death for civilians.
"Iraqi air force aircraft dropped hundreds of thousands of leaflets ... containing procedures and recommendations for citizens" in west Mosul and other ISIL-held areas, said Iraq’s Joint Operations Command.
These included "remaining inside houses and staying away from known (ISIL) sites such as headquarters, checkpoints, artillery positions and barracks, because they will be targets for our aircraft.
"Aerial bombing will target (ISIL) gangs and not civilians," it said in a statement.
The US-led coalition carrying out strikes against ISIL — which has admitted that it "probably" played a role in recent civilian casualties in Mosul — has said that the militants are forcing civilians into homes and then seeking to encourage air strikes on them.
ISIL has repeatedly targeted civilians with snipers, bombs and shelling in and around Mosul, and seized them for use as human shields.
The United Nations has said more than 300 civilians have been killed in the fighting during the west Mosul offensive, which began in February.

Source: The National