A Nigerian official says Boko Haram extremists have seized back the northeastern border town Marte and are attacking villages, weeks after the military said it had contained the insurgents in a forest stronghold.

Deputy Gov. Zannah Umar Mustapha of Borno state says hundreds of female suicide bombers are feared to have slipped into the state capital, Maiduguri.

He spoke Friday, a day after soldiers repelled an assault on Maiduguri by hundreds of insurgents that killed at least 36 people, according to hospital workers and anti-Boko Haram vigilantes. Civilian fighter Muhammad Gava says about 20 were civilians killed by Nigerian cannon fire.

Mustapha says it's clear some insurgents have fled and are hiding in communities. A multinational force and Nigerian troops last month had driven Boko Haram out of all towns.