The bombing was the second in two days. A car bomb aimed at a bus stand killed 13 people and injured 37 Thursday.
Police said three attackers were also killed in Friday's bombing, the Express Tribune reported. Six police officers were injured, and a spokesman for Lady Reading Hospital said two were in critical condition.
Investigators said the insurgents entered the C-Division police station, one of the largest police posts in Peshawar, and threw hand grenades at the security guards at the gate. When officers began firing at them, the three blew themselves up.
Abu Zarar Said, a spokesman for the Abdullah Azzam Brigade, said the group was responsible for the attack. He described it as a reprisal for the death of a militant leader, Badar Mansoor, who was killed by a drone in Waziristan.
Also Friday, a remote controlled bomb was set off near a police picket. One person was injured.