BANGKOK, Sept. 3 (Xinhua) -- An explosion caused by gas leak in a laundry in downtown Bangkok left eight people injured on Monday.

The blast occurred in the self-service laundry in early Monday when customers were queuing to use the machines. Three men and five women were were hospitalized.

The laundry, housed in a three-floor mansion, together with shops next to it and vending carts nearby, were severely damaged.

Witnesses said there was a strong smell of gas before the explosion. They asked a shop keeper to inform the owner of the laundry as the smell got stronger, but it exploded.

Six gas cylinders were found at the spot, of which four were used to heat the dryer and two were backups, according to police.

The laundry owner said the shop opened only three days and was in free promotion to attract customers.

Police said the owner would face a jail term of six months and a fine of up to 50,000 baht (about 1,515 U.S. dollars).