Militants raided a university in northwest Pakistan Wednesday, timing their attack to a ceremony at the school to ensure maximum casualties. They slaughtered at least 22 people, a provincial police authority said. The scent of burning metal hung in the air a few hours after the attack as a CNN crew made its way through the building where many were shot and wounded. Blood covered stairwells, the walls were pockmarked by bullets. Some of the students' laundry still hung in a courtyard. By Thursday, a day after the bloody attack occurred, Nasir Durrani, deputy inspector general of Khyber Pakhtunkhwa province, said that police were questioning around 50 people for connections to the attack. No arrests have yet been made. Militants had entered the university campus via a low wall at the back of the compound and made their way systematically across the grounds, throwing grenades and shooting, army spokesman Lt. Gen. Asim Bajwa said. Khyam Mashal, a student at the university, was in the boys' hostel on the campus, where he lives, when the militants attacked. He was sleeping when a friend woke him to tell him that terrorists were attacking the school. He says he was "shocked" that the attackers had breached the school's security. "I looked through the window so there were two, three people firing, and I think they were the terrorists," he said. "I'm so afraid... my country is not safe. I'm not feeling comfortable." Despite the conflicting statements from the Pakistani Taliban over responsibility, analysts say the attack probably is the work of the terror group. "We've seen consistent operations by the Taliban up in this area," CNN counterterrorism analyst Phil Mudd said. "I see this as simply as retaliatory, that is the Taliban saying, 'If you're going to bring Pakistani special forces and the army up into our turf, you're going pay a heavy price.'" The attack on the university was most likely to avenge military operations that have reduced the power of the Taliban, said Paul Cruickshank, a CNN terrorism analyst. The central Taliban organization will deny the attack for political reasons, Cruickshank said. "It's very confusing, but all part of the local dynamics," he said.