The suicide bomber who killed more than 100 people at a mosque in a police compound in the Pakistan city of Peshawar this week wore a police uniform and entered the high-security area on a motorbike, a provincial police chief said on Thursday.

The bomber behind Monday’s attack had been identified as a member of a militant network, Moazzam Jah Ansari, police chief of Khyber Pashtunkhwa province, told reporters. “I admit this was a security lapse. My men could not stop it. This is my fault,” Ansari said.