IRBIL, Iraq (AP) — Witnesses in the Iraqi city of Kirkuk say armed militants have attacked a local police compound and that fighting is underway.

They say multiple explosions have rocked the city so far in Friday's assault and that gunfire could be heard ringing through the city.

There were no immediate reports of casualties.

The attack comes as the Iraqi government and Kurdish forces are making a major push to drive Islamic State militants from Iraq's second-largest city of Mosul. The witnesses spoke on condition of anonymity as they are concerned for their safety.

Kirkuk is an oil rich city some 290 kilometers (180 miles) north of Baghdad that is claimed by both Iraq's central government and the country's Kurdish region.