So far, no one has claimed responsibility for the bombing at the Erawan Shrine, while police are refusing to rule anything or anyone out. National Police Chief Somyot Pumpanmuang said on state-run TV that authorities had been warned about possible attacks, but they didn't know where or when they might occur.
While the capital has never before witnessed such a devastatingly brutal attack, Thailand's recent history has been turbulent to say the least, with the country currently governed by a military junta following last year's coup.
Thai security forces have been waging a decades-long campaign against a Muslim insurgency in the south of the country that has claimed thousands of lives. Well-armed, motivated and increasingly audacious, insurgents in the southern provinces of Pattani, Yala, Narathiwat, Satun and Songkhla -- once part of an independent Malay Muslim sultanate until they were annexed by Thailand, then called Siam, in 1909 -- have emerged with a clear goal: the creation of a separate Muslim state for the region's 1.8 million Muslim ethnic Malays.
While calls for secession have simmered since then, an insurgent raid to steal weapons from an army camp in January 2004, led to a crackdown by the Thai military, which sparked the modern insurgency.
The Thai government has sent more than 150,000 soldiers to the region to protect it from an estimated 3,000 to 9,000 rebel fighters -- or juwae, as they are called locally -- according to estimates from human rights groups. But the conflict has never spread out of the southern provinces.
"This is not their style at all," said CNN global affairs analyst Bobby Ghosh, referring to the insurgents. "Their complaints are very local, and they have tended to attack military and security targets. They have not really committed a terrorist attack of this nature against civilians, much less tourists. This does not seem to bear their fingerprints."
Joseph Liow, of the Brookings Institution, agreed it would mark a significant departure from previous tactics.
"For a number of years, people have been speculating whether the elements involved in the insurgency in the south will be hitting other targets beyond the southern provinces, but we've never seen that happen. And it would be intriguing, if indeed there is any link, why this would happen now."
Paul Chambers, from the Institute of South East Asian Affairs at Chiang Mai University, said recent talks between the two sides also made an attack by southern elements unlikely.
"Almost all of the insurgent groups have been involved in a dialogue with the military government, so it's illogical for them to want to have a bomb."
Reaction against military rulers
When General Prayut Chan-ocha announced the imposition of martial law on May 20 last year, just days after Prime Minister Yingluck Shinawatra
was removed from office by the country's Constitutional Court, he said it was to calm tensions after rival political factions couldn't reach an agreement to govern. The country had been divided between populists, many of them rural and poor -- and loyal to Shinawatra and her ousted brother, Thaksin -- and a largely urban middle class and elite in Bangkok partial to the nation's royal establishment.
Thaksin's removal as Prime Minister back in 2006 led to a broad-based opposition movement that came to a head with widespread demonstrations in parts of Bangkok in 2010. More than 90 people were killed during clashes with security forces.
Soon after the military took control last year, Prayut pledged that he would work to return an elected government to power. Elections were initially planned for October this year but were pushed back to the end of 2016. A new constitution, written by a committee appointed by the ruling junta, has been drafted, but critics say it is anti-democratic.
The former military chief, who has since become Prime Minister, then guaranteed himself almost absolute power when martial law was replaced with a controversial security law known as "Article 44."
Described by critics as a "dictator's law," it gives Prayut unchecked control over all branches of government and grants him immunity from prosecution. Thailand's military rulers insist the measures are needed to maintain stability.
Would the political climate inspire such a violent backlash?
"There are political groups that are opposed to military rule, but they're democrats and this is not their style either," said CNN analyst Ghosh. "They don't go around bombing innocent civilians. And hurting Thailand's economy, which this will do, is the last thing that they would want."
But Chambers, from the Institute of South East Asian Affairs at Chiang Mai University, said the attack could point to rogue elements within the military or police.
"You have to look at three things: Who in Thailand has the capability to get this done? Who had the most to gain? And why would they do it now?
"I think the answer points to elements within the military or the Thai police ... because right now there's been some reshuffles of certain military people and intermediate-level troops are not very happy about those reshuffles."
In a statement issued to media Tuesday, the Prime Minister said it "is apparent that there are active individuals or groups that harbor the intention to damage Thailand, who may be pursuing political gain or other intentions by damaging the economy and tourism. The Royal Thai Government shall expedite all investigative efforts to find the perpetrators and bring them to justice."
Last month, Thailand was criticized for deporting more than 100 Uyghur refugees to China, with human rights activists warning that they would face persecution.
The Uyghurs are a predominantly Muslim ethnic group who live in Xinjiang, a province in Western China the size of Iran that is rich in natural resources, including oil. Over the decades, waves of Han Chinese migrants -- China's dominant ethnic group -- arrived in the region, displacing Uyghurs from their traditional lands and fueling tensions.
Activists say a campaign is being waged to weaken the Uyghurs' religious and cultural traditions and that the education system undermines use of the Uyghur language.
The decision to deport the Uyghurs from Thailand sparked protests in Turkey, with which the Uyghurs share linguistic and cultural similarities. The Thai Embassy in Ankara and its consulate in Istanbul had to be closed temporarily after pro-Uyghur protesters stormed the latter.
"A possibility is it's Uyghur terrorists, or Uyghur people upset at the regime for deporting many Uyghur people to China -- after all there were Chinese killed in this attack. But I think this is very unlikely," said Chambers.
While tensions in China's restive Xinjiang have spilled over into violence between security forces and what Beijing has described as "religious extremists" and "separatist forces," there have been no reports that violent groups within the Uyghur movement have launched attacks of this type abroad before.