The Pakistani city of Peshawar has begun burying its dead after a Taliban attack at a school killed at least 132 children and nine staff.
Mourners crowded around coffins bedecked with flowers, while other families waited at hospitals for news.
Prime Minister Nawaz Sharif declared three days of mourning and Pakistan's army struck at militants in the region.
World leaders voiced disgust at the Taliban's deadliest attack to date, which even its Afghan allies disowned.
According to the army, Tuesday's attack was carried out by seven Taliban attackers, all wearing bomb vests.
They cut through a wire fence to enter the school from the rear and attacked an auditorium where children were taking an exam.
Gunmen then went from classroom to classroom at the military-run school, shooting pupils and teachers where they found them, survivors say.
The siege at Peshawar's Army Public School, which teaches boys and girls from both military and civilian backgrounds, lasted eight hours.
A total of 125 people were wounded, according to the army before all seven attackers were killed. Hundreds of people were evacuated.
The Pakistani Taliban sought to justify the attack by saying it was revenge for the army's ongoing campaign against them. The school was chosen as a target, the militants said, because their families had also suffered heavy losses.
In line with the Islamic custom, mourners began burying victims as darkness fell.
The bier carrying the shrouded body of one teacher was strewn with flowers as men crowded around it.
At the funeral of one pupil, his father told the Associated Press news agency: "He was only 15 years old and was in the eighth grade.
"I was in the court when I received a call about the incident and then rushed towards the hospital... He got a bullet right in his chest and another bullet hit his hand. I am sorry I can't talk any more about it."
Sajid Khan, uncle of 10-year-old victim Gul Sher, told AFP news agency his nephew had plans to become a doctor.
"We cannot take the revenge from the terrorists but we pray to Allah to take the revenge," he said.
'Our children's blood'
Prime Minister Sharif also pledged to avenge a "national tragedy unleashed by savages".
"We will take revenge for each and every drop of our children's blood that was spilt today," he said.
Malala Yousafzai, the 17-year-old who was shot by the Pakistani Taliban for championing girls' rights to education, also condemned "these atrocious and cowardly acts".
"Innocent children in their school have no place in horror such as this," she said.
In line with the national mourning, Pakistani embassies worldwide will have their flags lowered to half-mast and books of condolences will be opened.
The military response is already reported to have begun.
Pakistani military spokesman Asim Bajwa announced in a tweet that 10 air strikes had been carried out in the Khyber region, along with other action, as yet unspecified.
Pakistani Taliban spokesman Mohammad Khurasani said the militants had been "forced" to launch the attack in response to army attacks.
He accused the military of killing the children and womenfolk of Taliban fighters and burning their homes.
Hundreds of Taliban fighters are thought to have died in a recent government offensive in the Khyber area and North Waziristan, regions close to the Afghan border.
Deadly attacks in Pakistan
16 December 2014: Taliban attack on school in Peshawar leaves at least 141 people dead, 132 of them children
22 September 2013: Militants linked to the Taliban kill at least 80 people at a church in Peshawar, in one of the worst attacks on Christians
10 January 2013: Militant bombers target the Hazara Shia Muslim minority in the city of Quetta, killing 120 at a snooker hall and on a street
28 May 2010: Gunmen attack two mosques of the minority Ahmadi Islamic sect in Lahore, killing more than 80 people
18 October 2007: Twin bomb attack at a rally for Benazir Bhutto in Karachi leaves at least 130 dead. Unclear if Taliban behind attack
In Afghanistan itself, the local Taliban described the school attack as un-Islamic.
The Afghan Taliban are currently stepping up their own attacks in Afghanistan and share roots with the Pakistani Taliban and usually share the same ideology too, the BBC's Mike Wooldridge reports from Kabul.
But their spokesman, Zabihullah Mujahid, said that they were sending their condolences to the families of the children killed in the Peshawar attack and that they shared their sadness.
US President Barack Obama said terrorists had "once again shown their depravity" while UN Secretary General Ban Ki-moon said it was "an act of horror and rank cowardice".
India's Prime Minister Narendra Modi offered his country's "deepest condolences".