The United States on Thursday condemned the abduction of hundreds of children by gunmen from Government Science Secondary School, Kankara, Katsina State, on December 11.
It urged the government to hold those responsible accountable" to the full extent of the law".
The US Department of State condemned the abduction in a statement issued by a spokesperson, Cale Brown, after the release of the abducted students on Thursday.
"We offer our sincere sympathies to the families of the missing students and the security guard killed in the attack.
"School should be a safe place where children can learn and thrive," it said.
The governor of the state, Aminu Masari had on Saturday also ordered the immediate closure of all boarding secondary schools in the state and pleaded with parents to remain calm as the government was making efforts to ensure the safe return of the students.