The explosions occurred around midnight last night at Khyber Super Market in Peshawar, the capital of Khyber-Pakhtunkhwa province that has repeatedly been targeted by militants over the past few years.
Provincial Information Minister Mian Iftikhar Hussain told the media that 34 people were killed and 94 others injured in the attack.
Officials at the Lady Reading Hospital described the condition of 21 wounded as serious. Doctors made an emergency appeal for people to donate blood.
The first blast was a low intensity one and injured a few people, SSP (Operations) Ijaz Ahmed Khan said.
The second explosion, which was more powerful, occurred a few minutes later when a large number of people, including journalists and policemen, had gathered in the area.
The explosions occurred within minutes of each other. The second blast was caused by an improvised explosive device hidden in a motorcycle.
Several journalists, including the local bureau chief of a news channel, and eight policemen, including two officers, were among the injured. Officials said they were out of danger.
No group claimed responsibility for the blasts, which triggered a blaze that was extinguished by fire fighters.
Rescue efforts were hampered by a power cut in the area. Security forces cordoned off the area and launched a search operation.
The market was crowded at the time of the blasts as it has several popular eateries and hotels. Footage on television showed debris and bloodstained clothes lying at the site of the blasts.
A wounded man tried to crawl to safety as huge flames rose into the sky behind him.
An electricity transformer burst into flames and the fire engulfed nearby buildings. Several shops were reduced to heaps of rubble and mangled metal. The blasts blew out the windows of nearby residential buildings.