Photo taken on Oct. 7, 2012 shows the site of an explosion in a residential building in the Nanshi District of Baoding, north China's Hebei Province. The explosion took place on Saturday afternoon.(Xinhua/Wang Xiao)

The death toll has climbed to three after an explosion triggered probably by illegal manufacturing and storage of detonators at a residential building in north China.

The accident that happened at around 3 p.m. Saturday in Baoding City, Hebei Province also left more than 34 people injured, local police said Sunday.

Police found self-made detonator shells at the explosion site of the six-storey building in Dongwuyao Village. Detonator shells and materials of explosives were also discovered in the building's basement.

Police suspected illegal manufacturing and storage of detonators might have caused the blast.

Four of the injured have left hospital after treatment.

Part of the building collapsed after the blast.

Witnesses said heavy smoke was seen following the explosion, which shattered window glass of buildings 200 meters away.

An overhaul of illegal storage of explosives has been staged across the city following the blast, police said.