The car bomb at the Central Festival shopping centre on Koh Samui late Friday night might have been caused by a local business or political conflict, according to a report from the government committee on solving problems in the southern border provinces.
The committee, which consists of southern military and police authorities in the lower South, reported that the bombers might be from the far South because evidence from the scene showed expertise in car bomb making and the pickup truck used to carry the bomb had been stolen from the southern border province of Yala.
The committee raised the question of whether the bombers had been hired by a local resident on Koh Samui and whether the bombing was not intended to hurt anyone as it was set to explode at about the time the centre closed.
- See also: Government blames 'coup critics'
- EDITORIAL: Section 44 proves a failure
- Samui bomb threatens tourist confidence
It said the bomb probably weighed about 80 kilogrammes and was placed inside a 15kg cooking gas cylinder. A Samsung Hero mobile phone was wired to detonate the bomb at a set time. The mobile phone of this series does not require a SIM card to operate.
The bomb was connected to a 12-volt motorcycle battery and shrapnel was made from chopped steel rods, four millimetres in diameter, of various lengths.
The Mazda truck bore fake licence plates made from painted cardboard paper. It was parked near a pillar of the shopping centre, possibly to maximise damage to the structure of the building.
The bombers might also have hoped for other cars to be parked next to the pickup to increase the magnitude of the explosion, the report read.
The brown truck had been stolen from Abdulrosa Dumeedae, a 52-year-old driver with La-ae tambon administrative organisation in Yaha district of Yala, at about 8am on March 31. Authorities had questioned him in depth because he refused to give useful information and had delayed his report of the robbery for two hours.
During the dramatic theft of Mr Abdulrosa's car, about eight robbers dressed like paramilitary rangers carried war weapons and wore bullet-proof vests.
The Koh Samui explosion injured two Thai men and two Thai women. Three other women including a 12-year-old foreigner were shocked and fainted.
Earlier reports on the attack linked it to national political conflicts and a man in Nonthaburi was detained for questioning as his Facebook message seemed to foreshadow attacks in Surat Thani province late Friday night.
Narin Umnongbua, reportedly calling himself "M Redshirt", wrote: "A lot of stuff is being prepared for Surat Thani tonight. Who wants to be in? Let's ruin them."
Meanwhile, the Surat Thani Co-operative in Phunphin district was badly damaged at about the same time as the Koh Samui attack.
Deputy government spokesman Maj Gen Sansern Kaewkamnerd said authorities located Mr Narin at a camp for municipal workers in Bang Kruai district of Nonthaburi and he gave useful information on many issues.
