Thailand's armed forces shared a screengrab from drone footage of the explosion's aftermath
The explosion in Sungai Kolok, on the Malaysian border, seriously injured at least 115 people and is thought to have been caused by construction work.
Residents described hearing a huge explosion at around 15:00 (09:00 BST).
The force shook buildings, shattered windows and collapsed roofs, sending a massive plume of smoke into the air.
The explosion has also destroyed a large part of the town in Narathiwat province.
The market fire has been brought under control and a preliminary investigation indicates a "technical error" in steel welding during construction work on the building was responsible, local governor Sanon Pongaksorn said.
At a press conference on Sunday, he said the death toll stood at 10, but that it may rise because rescuers had found parts of two bodies that they could not identify.
Seksan Taesen, an eyewitness who lives 100m (330 ft) from the market, said he was at home when he heard a "loud, thunderous noise and my whole house shook".
"Then I saw my roof was wide open. I looked outside and I saw house collapsing and people lying on the ground everywhere. It was chaos," he told AFP.
Accidents involving fireworks in South East Asia, which are commonly used in the region to commemorate big events, are not unusual.
One in a factory in Indonesia six years ago killed 49 people. Another five days ago killed one woman and injured 10 more in northern Thailand.
Despite public pressure to improve safety, Thailand still has a poor record of accidents on its roads, construction sites and in the work place.
Enforcement of regulations is all the more challenging in Sungai Kolok - a notoriously rowdy border town where anything goes, located in a region of Thailand which is still blighted by an active armed insurgency.
-- Courtesy of BBC News