Taliban have ambushed a Pakistani school bus, killing four boys and the driver in a hail of bullets and rocket fire on the outskirts of the northwestern city of Peshawar.
The children studied at an elite English-language school of a type reviled by hardline Islamist militants who oppose what they see as imported Western, secular education.
Two seven-year-old girls on the bus were also wounded, officials said.
The children were targeted in the Matani area close to Pakistan's northwestern tribal belt, which the United States considers the most dangerous region on earth and an al-Qaeda headquarters.
Tehreek-e-Taliban Pakistan (TTP) claimed responsibility for the attack saying it was the work of their Khyber chapter.
Bombings by Taliban and al-Qaeda-linked networks have killed more than 4630 people since 2007, destabilising the nuclear-armed state.
"Gunmen opened fire on a school van and also lobbed a rocket in Peshawar's suburb of Matani," senior police official Ejaz Khan told AFP.
Police said the bus was taking children home at the end of the school day, which in Pakistan finishes in the early afternoon.
Senior police official Kalam Khan said from the scene that four boys were killed along with the bus driver.
"The gunmen were waiting for the bus in fields and attacked when it came close. They fired a rocket and then fired bullets on the van," he said.
TTP spokesman Ehsanullah Ehsan said the purpose of the attack "was to punish the Kakakhel tribe who formed a lashkar (army) against us", referring to state-backed anti-Taliban militias.
Outside Peshawar's main hospital, Jahandar Shah, whose seven-year-old son Jamal died, sobbed uncontrollably and smothered his forehead in kisses as he tried to pull his blood-stained body from a stretcher onto his lap.
He blamed the government, allied to the US-led war on terror, and the Taliban, for his son's death, screaming: "What was the fault of this innocent child? Why did you kill him?"
Shoaib Khan, a 15-year-old student wounded in the attack, said gunmen first opened fire on one side of the road, then waited for pupils to start fleeing before widening the attack.
"I started bringing kids out of the bus when the gunmen began firing from the other flank as well," he said.
"Then I was also injured and fell unconscious. I don't know what happened next."
Habib Khattak, a doctor at Peshawar's Lady Reading Hospital, said 18 wounded were admitted after the attack, 12 of them children and the others teachers and passers-by.
The vehicle belonged to the private Khyber School. Fee-paying, English-language schools are almost universally patronised by Pakistan's middle and upper classes, with English widely used by the federal government.
The school told AFP it had taken some precautions but that it had never been openly threatened by militants who have a presence in the area.
"We received no threatening letter," said deputy head Salman Ahmed.
"We ourselves adopted measures for the safety of the children. We stopped singing classes and the school band playing music during the morning assembly because we know militants are active in the area."
In the district of Lower Dir bombers on Tuesday also assassinated a local leader of Pakistan's main ruling Awami National Party (ANP) in the northwest, blowing up his vehicle.
Lower Dir borders the once Taliban-infested Swat valley, where a sweeping army offensive two years ago appeared to reverse a local Taliban insurgency.
In 2009, 30,000 Pakistani troops went into battle against Taliban fighters who had terrorised people in Swat and parts of Dir for two years with a campaign of beheadings, violence and attacks on girls' schools.
The army declared the region back under control in July of that year and said the rebels had all been killed, captured or had fled.
The army is now trying to encourage tourists to return to Swat, once beloved by Pakistani and Western holidaymakers for its stunning mountains, balmy summer climes and winter skiing easily accessible from the capital Islamabad.
