Witnesses in northern Burkina Faso say Islamic extremists opened fire on a group of police officers, critically wounding one of them.

One witness, who insisted on anonymity for his safety, said the gunmen arrived in a pickup truck late Tuesday in Koutoukou near the border with Mali. He said Wednesday that the militants screamed "Allahu akbar," or "God is great" in Arabic, before storming the police station Tuesday night.

The violence comes four months after Burkina Faso's deadliest jihadi attack when several extremists attacked a hotel and cafe in the capital popular with foreigners, killing 30 people.

The far north of Burkina Faso near Mali remains dangerous: A Romanian man kidnapped in the region last year remains captive as does an Australian doctor who ran a clinic in the area.