GENEVA (AP) — The U.N.'s migration agency says two of its staffers were among 11 people killed in an attack by Boko Haram militants on a military base in northeastern Nigeria.

The International Organization for Migration said Friday that "a large number" of Boko Haram members attacked the base in Rann, in Borno state, a day earlier with automatic weapons, rocket-propelled grenades and gun trucks.

At a U.N. briefing in Geneva, IOM spokesman Joel Millman said the two staffers, Ibrahim Lawan and Yawe Emmanuel, were among three humanitarian workers killed. Four soldiers and four mobile police also died, and another three humanitarian workers were injured.

IOM Director of Operations and Emergencies Mohammed Abdiker said in a statement that the agency was "outraged and saddened" by the attack.