At least 21 people were injured in a fire and a subsequent explosion in a building in the northern German city of Hamburg on Tuesday morning, German media Focus Online reported.

According to a fire department spokesman, the fire broke out early in the morning in a carpentry workshop in a former bunker building. The subsequent explosion occurred while firemen were trying to extinguish the fire.

At least 21 people were injured in the accident, including six firefighters, some of whom in serious condition, the spokesman was quoted as saying.