TIKRIT, Iraq (Reuters) - At least six people were killed and 42 wounded when a suicide bomber detonated a car full of explosives at a restaurant on a highway near the Iraqi city of Tikrit on Wednesday, police and medical sources said.

Police said the attacker targeted the Qala’a restaurant which is usually frequented by security forces members and paramilitary fighters.

Most of the casualties were a group of Iraqi tourists traveling on board of a bus that stopped by the restaurant, police and medical source said.

No group has claimed responsibility, but Islamic State militants often carry out such attacks.

Iraqi security officials have said Islamic State is likely to wage an insurgency in Iraq after its self-proclaimed caliphate all but collapsed and the militants were dislodged from large areas of the west and north of the country.

The group’s fighters have since then waged a campaign of kidnappings and killings.