Multiple suicide bomb blasts have killed at least six people and wounded 18 others in the northeastern Nigerian city of Maiduguri, security sources told Al Jazeera.

The attacks happened around 03:30 GMT on Wednesday at the Muna Garage area on the outskirts of the city.

Two suicide bombers blew themselves up at an unofficial camp for displaced people, while a third bomber was killed by his explosive device before he could reach his target.

Those wounded were taken to hospital to receive treatment.

There was no immediate claim of responsibility but Maiduguri has been frequently targeted by fighters of the Boko Haram armed group.

According to eyewitnesses, the bombers had sneaked into the camps late on Tuesday night alongside those who sell charcoal to refugees, who use it to cook their food.

Most of the people living there are those who have fled their homes due to the spate of attacks by Boko Haram in the country’s northeast.

On Tuesday, Nigerian President Mohammadu Buhari met security chiefs in the capital Abuja to review the security situation in the country. The nearly seven years Boko Haram crisis topped the agenda of the review, according to a presidential aide.

[Source: Al Jazeera and news agencies]