Nigeria's National Emergency Management Agency says troops have gunned down a suicide bomber at a transit camp for refugees from Boko Haram in the northeastern city of Maiduguri.

The Saturday attack is the sixth in three weeks in the Nigerian city that was the birthplace of the Islamic extremist uprising that has killed more than 20,000 people in seven years. Security forces have foiled most of the attacks.

On Friday, five suicide bombers targeted a police checkpoint and a bus station near the transit camp, killing four of themselves and two civilian self-defense fighters. The fifth bomber was arrested.

PR Nigeria news agency reports that Saturday's attacker was shot as he tried to detonate himself near the same camp.

Boko Haram has recently stepped up attacks after a months-long lull.