Five workers sustained burns and other injuries Thursday when an explosion tore apart a warehouse owned by a transport company in Kusatsu, Shiga Prefecture, police said.

The warehouse was immediately consumed in flames following the 11:30 a.m. blast, with the blaze spreading to two neighboring warehouses. All three warehouses are owned by Kyoto-based firm Fushimi Transportation.

Masaru Umezu, 56, sustained serious burns to the face and hands, while Koichi Okada, 42, suffered a fractured breastbone.

The fire leveled all three warehouses, which had a total floor space of about 6,300 sq. meters, before being extinguished about four and a half hours later.

The warehouse in which the initial explosion occurred apparently contained rice, police said. They added that the cause of the blast has yet to be determined.