There must be a preparation for materials and explosives," Somyot said. "There must be people who scout the route. There must be people who survey the site, people who would cover and look after the bomber. There must be people who know (the) escape route and take the bomber to do it."
Even though police say at least one foreigner may have been involved in the attack, the operation is unlikely to be linked to international terrorism, Col. Winthai Suvaree, a spokesman for Thailand's ruling military junta, said Thursday.
There has been no claim of responsibility for the bombing. Thai authorities haven't said what they think the motive for it might have been, other than making vague references to unspecified people or groups who want to hurt Thailand's tourism industry and economy.