Boko Haram invaded the restive northeastern Nigerian city of Gombe on Saturday and warned residents against voting in next month’s elections as the extremists defied regional force aiming to pursue them.

Boko Haram invaded the restive northeastern Nigerian city of Gombe on Saturday and warned residents against voting in next month's elections as the extremists defied regional force aiming to pursue them.

Residents said the attackers later left the city and stormed another area some 40 kilometers (25 miles) away, where they burned homes.

The violence prompted the state governor to impose an around-the-clock curfew.

Witnesses said the extremists stormed the city at around 9:00 am (0800 GMT) and advanced without any resistance from the security forces. It was unclear if there were casualties.

A Nigerian fighter jet encircled the city but did not appear to attack the insurgents, said witness Kabiru Na-Gwandu, adding that he had received a call from friends outside of Gombe warning him the gunmen were on their way.