They arrived in a taxi, he said.
The officer said the maker of the bomb was professional, judging from the handling of the bomb to the place, while the planter of the bomb was also a very calm person.
He believed moire than two persons were in connection with the bombings.
If investigation implicated more persons, they would be all arrested, he said.
He also said the bombing was politically motivated as 80% of bombing incidents in the past involved politics with intent to disturb peace and order.
He said the perpetrators chose Siam Paragon as their target in the downtown area for many reasons,one if which was to defy law enforcement authorities.