The incident happened in the Khyber tribal district of the province where a suicide bomber blew himself up when a policeman deployed at the main gate of the police station stopped him, the Khyber police said in the statement, reported Xinhua.
The police guard was killed on the spot, said the police.
As soon as the police gathered at the site, the second suicide bomber also blew himself up, injuring 10 policemen.
The injured police officers were shifted to a nearby hospital where several of them are in critical condition.
No group has claimed responsibility for the attack yet.
A heavy contingent of police and security forces reached the site and cordoned off the area for investigation.