Story highlights Police cadets were sleeping in barracks when militants attacked, killing 61

ISIS says it was behind attack; military officials have blamed another militant group

Quetta, Pakistan (CNN) Cadets at a police training academy in Pakistan awoke to the horror of suicide bomb-wielding terrorists in an attack late Monday that killed 61 and injured 117.

"We were sleeping when terrorists attacked the center," said Asif Hussain, a cadet who was in the academy's barracks at the time.

He said the cadets had no guns and were powerless to fight back when the militants struck through the window.

Sarfraz Bugti, home minister for Balochistan province, said three attackers were killed during the assault in Quetta, which targeted a hostel at the academy where hundreds of police recruits were sleeping.

During the hours-long operation that followed, security forces killed one attacker, while two others died when they detonated the bombs they were carrying, he said.