BANGKOK, July 29 (AFP) - An explosion ripped through a firework warehouse in Thailand on Saturday (Jul 29), killing nine people and injuring more than 100, a senior official told AFP.

The blast in the town of Sungai Kolok in the southern province of Narathiwat is thought to have been caused by welding during construction work on the building.

"A warehouse storing firecrackers in Sungai Kolok exploded this afternoon, the latest number is nine dead and 115 injured," Narathiwat governor Sanon Pongaksorn told AFP.

"The fire is now under control. Preliminary investigation suggests the cause is a technical error during the steel welding process, as the building is under construction."

Footage on local media showed a huge plume of smoke rising into the air and numerous shops, homes and vehicles badly damaged by the force of the blast - some ablaze and some with their roofs blown off.

"I was playing with my phone inside the house then suddenly, I heard a loud, thunderous noise and my whole house shook," eyewitness Seksan Taesen, who lives 100m away from the warehouse, told AFP.

"Then I saw my roof was wide open. I looked outside and I saw (a) house collapsing and people lying on the ground everywhere. It was chaos."

Thailand has a poor safety record in the construction sector and deadly accidents are common.

Last month two people were killed when a road bridge under construction in Bangkok collapsed.