Three suicide bombers set ablaze three fuel tankers in the center of Nigeria’s northeastern city of Maiduguri before dawn Friday, just days before a planned visit by the U.N. Security Council, ABC News reported.

According to Washington’s Top News, the Police Chief stated that Soldiers fired at one of the bombers, a teenage girl, to avert what could have been a major attack on the city’s main fuel depot.

The attack, outside a gas station opposite the northeastern headquarters of the Central Bank of Nigeria, killed only the three bombers, an elderly woman bomber who blew herself up beside a stationary tanker loaded with fuel around 3 a.m. was accompanied by a teenage boy and girl who continued down the road toward the fuel depot until they were challenged by soldiers.

Officials blamed Boko Haram insurgents who many times have attacked Maiduguri, the birthplace of Nigeria’s homegrown Islamic extremist group.

Increased security by Nigerian soldiers and civilian self-defense fighters has averted many suicide bombings in recent months.

The attack comes just days before the U.N. Security Council is expected in Maiduguri as part of a four-nation tour of countries in the Lake Chad Basin devastated by the seven-year Boko Haram uprising that has killed more than 20,000.