Militants raided a university in northwest Pakistan on Wednesday, timing their attack to a ceremony at the school to ensure maximum casualties.
After security forces combed the campus block by block after the massacre, Mehmood Khan, provincial home minister of Khyber Pakhtunkhwa, said 19 civilians were killed, along with four terrorists. He expects the number of civilian deaths to increase.
Earlier, an army spokesman said that 21 civilians had been killed.
The attack took place at Bacha Khan University in Charsadda, Peshawar, less than 40 kilometers (25 miles) from where the Pakistan Taliban slayed 145 people, including 132 children, in a school attack in December 2014.
It's unclear whether the group was responsible for the Wednesday incident.
One Pakistan Taliban spokesman, Umar Mansoor, said the attack was in retaliation for military operations against the group. Mansoor was also the mastermind behind the December 2014 attack, Pakistan's DawnNews reported.
But another spokesman, Mohammad Khurrassani, from the Pakistan Taliban's central organization, disavowed any role.
We "strongly condemn the attack on Bacha Khan University in Charsadda and disown the attack, saying this is not according to Shariah," Khurrassani said.
Caught off guard
Wednesday was the 28th anniversary of the university's founder, Abdul Ghaffar Khan, a 1920s Pashtun independence activist and pacifist also known as Bacha Khan. Guests were gathered at the university to pay tribute to the man when the militants came, said student Zahoor Khan.
The attackers threw grenades, pushed their way onto campus and opened fire, army spokesman Lt. Gen. Asim Bajwa said.
Khan said he saw his chemistry professor shot while advising students to stay inside.
A student told DawnNews the attackers were in his own age group.
"The attackers were like us -- they were very young. They carried AK-47 guns. They wore jackets like the forces do," said the student, who added that dozens of students were still asleep in their rooms because they didn't have class.
"There was firing between attackers and security forces," the student told DawnNews. "After everything was over, the army men knocked on our room and told us we were safe."
Troops pour in
In the aftermath, troop transporters pulled up to the gates of the university and entered campus with heavily armed soldiers, video from the scene showed. Other soldiers combed the school's outer walls with guns held at ready.
Ambulances swarmed to the campus. As rescuers rushed to put people on stretchers, injured people who could stand on their own walked past them in the opposite direction.
Some of them held on to others for support. Some cried openly.
Nearby, groups of men carried caskets through the crowd, and ambulance workers rushed back to their vehicles with the injured on their gurneys.
Who the Pakistan Taliban are
The Pakistan Taliban, formally known as Tehrik-i-Taliban Pakistan, are separate from the Taliban in Afghanistan but hold close ties to them and to al Qaeda.
The TTP follows its own, different goals, but its tactics are the same as the Afghan Taliban's. Its main target is the Pakistani military and the state, which it would like to overthrow and replace with Sharia law.
The TTP arose in the early 2000s when the Pakistani military began hunting diverse militant groups in the tribal regions near the Afghan border. In reaction, Pakistani militants with ties to the Afghan Taliban galvanized into a Taliban of their own.
Prime Minister's statement
"Prime Minister Muhammad Nawaz Sharif is deeply grieved over the sad incident of terrorists' attack on Bacha Khan University, Charsada, which has reportedly resulted into the loss of precious human lives and injured many others," a statement from the Prime Minister's office read.
"While condemning the cowardly attack of the terrorists, the Prime Minister said that those killing innocent students and citizens have no faith and religion."
The past few days have seen an increase in militancy in the region, including an attack on a checkpoint in Khyber Agency, a region west of Peshawar that borders Afghanistan, where 10 people were killed and 36 others injured.