Islamic State militants launched deadly attacks in the northern province of Kirkuk Friday, days after Iraqi forces began an offensive to recapture the extremist group’s stronghold of Mosul.

Provincial security officials said suicide bombers staged simultaneous predawn strikes on a police headquarters and other police targets in the provincial capital of Kirkuk and surrounding districts. They also attacked checkpoints, police patrols and a power station, these officials said. Authorities have imposed a curfew on the province until further notice.

Islamic State has suffered a series of losses of the land it captured two years ago in Iraq and Syria. As the group has been squeezed out of its self-declared caliphate, or religious empire, it has increasingly turned to the kind of hit-and-run guerrilla attacks seen Friday.

The attacks in Kirkuk demonstrate that the group can still strike with deadly force across the country, and bring terror to areas it doesn’t hold, even as the Iraqi military picks up the tempo of its operations.

The jihadist militants now face a grave threat as a U.S.-led coalition and Iraqi forces drive to push them from Mosul—their last remaining stronghold in Iraq. A paramilitary force dominated by Shiite militias said Friday they will join the fight for Mosul, deploying west of the city, with the aim of cutting off Islamic State supply lines from and escape routes to Syria.