Education campaigner and Nobel Peace Prize winner Malala Yousafzai has led condemnation of the "atrocious and cowardly" attack on a school in Pakistan which claimed the lives of at least 141 people and left scores injured.
The teenager joined a stream of western politicians and campaigners in criticising the Pakistani Taliban, who claimed responsibility for opening fire on the Army Public School in the city of Peshawar yesterday.
"I am heartbroken by this senseless and cold-blooded act of terror in Peshawar that is unfolding before us," said the 17-year-old, who was shot in the head by the Taliban in 2012 after speaking out for girls' rights to education.
"Innocent children in their school have no place in horror such as this.
"I condemn these atrocious and cowardly acts and stand united with the government and armed forces of Pakistan whose efforts so far to address this horrific event are commendable."
The attack took the lives of at least 141 people, the vast majority of them children.
At least 114 people were injured in the attack, deemed a "revenge" strike after Taliban members where killed by the Pakistan military.
David Cameron and Barack Obama were among those to denounce the bloody massacre.
The British prime minister described the scenes as "deeply shocking".
"It's horrifying that children are being killed simply for going to school," he said.
The US president condemned the attack, describing it as "horrific".
He added: "By targeting students and teachers in this heinous attack, terrorists have once again shown their depravity.
"We stand with the people of Pakistan, and reiterate the commitment of the United States to support the government of Pakistan in its efforts to combat terrorism and extremism and to promote peace and stability in the region."
A Pakistani military source told US TV network NBC that at least 10 attackers wearing police uniforms and suicide vests stormed the army-run school yesterday. The gunmen were reported to have fired at random inside the school before the building was surrounded by Pakistani troops, who exchanged fire with the militants.
"They burnt a teacher in front of the students in a classroom. They literally set the teacher on fire with gasoline and made the kids watch," the source said. Most of the school's 500 children are understood to have been evacuated, but many were being held hostage in the building.
Gunfire and explosions were heard shortly after the militants entered the school at around 10am local time.
A number of teachers and a member of the security forces were believed to be among those killed. The school is sited on the edge of a military cantonment in Peshawar, and some of the pupils are thought to be the children of members of the armed forces.
Taliban spokesman Mohammed Khurasani said six suicide bombers had carried out the attack in revenge for the killing of Taliban members by Pakistani forces.