The bomber exploded his suicide vest at the Excise and Taxation Office in Mardan district of Khyber Pakhtunkhwa, about 50 km from here, District Police Officer Faisal Shahzad said.
Before the explosion, the bomber fired two shots which resulted in people, about 30 to 35 in number, scampering for safe places,the Shazad said.
The injured people were being shifted to nearby hospitals for treatment.
Police and security forces rushed to the site and cordoned off the area soon after the blast that occured around noon.