An explosion in Tokyo's Edogawa Ward has left 10 people injured and damaged nearly 40 buildings. Investigators suspect a buried gas cylinder may have been the cause. 

The Tokyo Fire Department said a blast was reported at a condominium construction site in Higashikasai residential district on Tuesday morning. 

A truck at the construction site was burned in a blaze before it was put out 4 hours later. More than 30 fire engines were deployed. 

The blast shattered windows and walls of a nearby convenience store, houses and other shops. Fire officials said at least 38 buildings within a 100-meter radius of the blast sustained damage. 

Police said that 10 people, including construction workers and residents in their 20s to 70s, complained of pain in their ears and throat, but their injuries were minor. 

When the blast happened, workers were driving piles into the ground for a new condominium building. Investigators said a cylinder for highly flammable acetylene gas was found damaged from underground. The gas is used for welding metals. They said gas may have leaked and caught fire. 

Police are looking into the reason why such a gas cylinder was buried underground. 

The area is close to Kasai Station on Tokyo Metro's Tozai Line and there are many condominiums nearby. At one point in time, authorities called on residents to evacuate from the area.