Boko Haram, which is based in the north and styles itself on the Taliban, is waging a low-level insurgency against Nigeria`s southern-dominated government.
The militants opened fire on a police station in Ashaka, a remote town in northeast Nigeria`s Gombe state, before moving on to hit the banks, Mohammed Kabir Mohammed, deputy police commissioner for Gombe state, said.
"Four policemen, including the DPO (district police officer), and three others were killed," he said.
"We have beefed up security in the area, the situation is calm, although no arrest has been made yet."
Boko Haram has been blamed for almost daily shootings and bombings that have killed hundreds of people in the past two years.
U.S. Under Secretary for Political Affairs Wendy Sherman urged Nigeria on Monday to tackle the Islamist insurgency by bringing jobs and development to the deprived region, and it pledged to support Abuja in the task.
The Islamists used to be confined to its northeastern heartland of Maiduguri, but has in the past six months radiated across the north and struck the capital a handful of times.
Suspected sect members burned down 10 schools in northeastern Nigeria last week, authorities say, in what would be a new front in the insurgency by a group whose name means "Western education is sinful". (*)
Editor: Kunto Wibisono
Copyright © ANTARA 2012
