The European Union has condemned the "horrific murder by terrorists" of dozens of people, mostly students, in an attack on a secondary school in Nigeria.
The attack, blamed on the rebel group Boko Haram, happened on Saturday at a school in Mamudo, Yobe, one of three states where the government declared a state of emergency in May in a push to rein in the group.
"I condemn in the strongest possible terms the horrific murder by terrorists of some 30 innocent children and a teacher early on Saturday morning in a school in Mamudo town in northeastern Nigeria," Catherine Ashton, the EU foreign policy chief, said on Sunday in a statement.
Ashton promised Nigerians her "solidarity and determination to help them bring security, peace and reconciliation to the north", and called for those responsible to be brought to justice.
Survivors of the dawn attack said gunmen rounded up students and staff at the school in Nigeria's restive northeast and placed them in a dormitory before throwing explosives inside and opening fire.
A hospital official in nearby Potiskum said 42 people were killed. A spokesman for Nigeria's military, which often underplays casualty figures, said 20 students and one teacher were killed.
Boko Haram, which means "Western education is a sin", has killed hundreds of students in attacks on schools in the region in recent months.
Nigeria launched a major offensive against Boko Haram on May 15, battling anti-government fighters in the states of Adamawa, Yobe and Borno.
The ongoing offensive has forced thousands of Nigerians from their homes into refuge in neighbouring countries of Niger and Cameroon.
Meanwhile, Yobe state has ordered the closure of all secondary schools after the massacre Saturday's massacre.
Ibrahim Gaidam, the state's governor, "directed that all secondary schools in the state be closed down from Monday 8th July 2013 until a new academic session begins in September," a government statement said.
The order came amid reports that soldiers involved in a shootout with fighters who were given refuge in one Nigerian village hut took revenge on the community by setting ablaze about 10 homes, according to refugees who fled to neighbouring Niger.
Their stories indicate a pattern of Nigerian security forces punishing entire communities, including innocent civilians.
Refugees spoke to an Associated Press reporter on a trip with Nigerian officials who are pleading with them to return home, visiting thousands who have fled across borders to escape an Islamic uprising and a military crackdown.
Deputy governor Zannah Mustapha of Borno state visited Niger on Saturday, days after visiting more than 20,000 refugees in Cameroon.
Mustapha promised "adequate security" would be provided to ensure their safety from further attacks in their northeastern hometown of Mallam Fatori.
The refugees, among 6,240 recorded in Niger, indicated they are as scared of the Islamic extremists as they are of the soldiers who are supposed to protect them.