Story highlights Suspected WWII-era aerial bomb explodes in Bangkok neighborhood, killing seven

Bomb discovered on a construction site and moved to a scrapyard, where it was sold

Scrap workers detonated the bomb accidentally after cutting into it with a blowtorch

WWII-era ordnance still discovered from time to time in Asian cities

Thai scrapyard workers accidentally detonated a suspected World War II-era bomb Wednesday, killing seven and injuring 19 after attempting to cut into it with a blowtorch.

The device was discovered at a construction site in Bangkok, and moved to a scrapyard before workers tampered with it, in an attempt to break it down into smaller parts.

Thai state news agency MCOT , quoting the the Bangkok Metropolitan Administration's Erawan Medical Center, said six people died at the scene. Another reportedly died before reaching the city's Mayo hospital.

The blast, in Bangkok's Lad Prao district, caused a ten foot-deep (3 m) crater in the scrapyard's warehouse, and damaged neighboring properties. The device was around 3 ft (1 m) long and weighed 500 lb (225 kg).

Local police commander Virasak Foythong told media that the scrap workers believed the bomb to have been defused.

"The workers at the warehouse thought the bomb was no longer active so they used a metal cutter to cut into it, causing the explosion."

Police said they suspected that the bomb was of World War II vintage but its origin was not determined. Both British and American bombers attacked Bangkok in 1944, while Thailand was an ally of Japan.