NEW DELHI: Vigils were held across Pakistan to mourn the death of at least 21 people killed in an attack on Bacha Khan University in Charsadda. Four suspected attackers also died in Wednesday’s brutal attack.

Inter-Services Public Relations (ISPR) Director General Lt Gen Asim Bajwa said major breakthroughs had been made in identifying the gunmen behind the attack, whilst a leading Tehreek-i-Taliban figure claimed responsibility. The TTP’s spokesperson, however, has denied involvement. In 2014 in Peshawar, the TTP attacked an army run school killing 130 people.

"When army reached the premises, all four attackers were alive. They were contained in the hostel and were eventually eliminated on the roof and the stairs," said the ISPR chief. “Their call logs were analysed and an intelligence picture was established, with most data having been collected," he said, adding that forensics and fingerprints of the attackers was shared with the National Database Registration Authority and an “intelligence picture is also being created with input from Nadra."

"We have gathered almost all relevant data on who they (attackers) were, from where they came and who supported them,” General Bajwa said, stopping short of revealing the identity or affiliation of the attackers. He did, however, indicate that the Taliban may be involved as he said, “We cleared the sanctuaries of terrorists after which certain people crossed the border towards Afghanistan and are operating from there. That aspect is also under investigation.”

The attack took place early on Wednesday, as gunmen entered Bacha Khan University in Charsadda, 50km (30 miles) from Peshawar, and opened fire on students and faculty as they gathered for a poetry event. Those killed were a professor, two gardeners, one caretaker and 17 students, a source told AFP.

The mastermind of the Peshawar school attack, Umar Mansoor, affiliated with the TTP’s Geedar group, claimed the attack in a post on his Facebook page, adding that four attackers were sent to the university. However, a spokesperson from the TTP, Mohammad Khorasani, issued a conflicting statement shortly after Mansoor's claim, condemning the attack as an act “against Shariah.”

The attack comes at a time when Pakistan is cracking down on militant outfits, with Operation Zarb-e-Azb in North Waziristan and Khyber-1 in Khyber Agency seeing consistent success. It also comes as Pakistan seeks to improve ties with India and Afghanistan -- two countries that have accused it of not doing enough to reign in terror, especially militant outfits that operate across the border in India and Afghanistan. Pakistan has recently detained Jaish leader Masood Azhar, following an attack on a military base in Pathankot, India. Pakistan is also currently in talks with Afghanistan, levelling pressure on a faction of the Taliban to enter into a peace dialogue with Ashraf Ghani’s government.

That said, there are reservations in all three countries regarding Pakistan’s commitment to taking action against terror groups, many of which it has harboured, and for differentiating between “good” Taliban and “bad” Taliban -- the former referring to groups active in India and Afghanistan, and the latter referring to groups like the TTP that are waging a war against the Pakistani state.

The Peshawar school attack in 2014 was a huge game changer as it levelled pressure on Pakistan to take action against militant groups in the country regardless of differentiation, and the Bacha Khan University may further this commitment.

Wednesday’s attack also has symbolic significance, as Bacha Khan University is named a Pashtun leader who believed in nonviolent struggle. The attack took place at a poetry recitle in Khan’s order, titled “Peace.”