Hamburg - At least 38 people were injured on Tuesday in a fire and subsequent explosion at a former air raid shelter in the northern German city of Hamburg, the fire brigade said.The fire broke out in a carpentry workshop inside the five-storey bunker, which is also used as a storage space for about 100 tons of essential oils. The explosion took place as firefighters were attempting to douse the flames.The cause of the fire and explosion in the densely populated Rothenburgsort district of Hamburg was still unclear.Of the 38 injured, 12 were firefighters. Nineteen people were being treated in local hospitals, while others received medical attention for smoke inhalation at the scene.The firefighting efforts were expected to last until the afternoon."At the moment we aren't sending anyone else into the buildings, because the situation inside is unclear," said a spokesperson for the fire brigade. "We plan to flood the bunker with foam to douse the flames."More than 60 people were evacuated from surrounding buildings.