Thailand's government has set up a "war room" to hunt down those responsible for Monday's deadly bombing of a Bangkok shrine, as the country's defence minister said the attack aimed to target the country's economy.

The explosion, which has killed at least 20 people and injured scores, detonated around 7pm local time at the crowded Erawan Hindu Shrine in the city's busy commercial district.

At least eight tourists from China, Hong Kong, Indonesia, Malaysia and Singapore are among those killed in the attack.

Defence Minister Prawit Wongsuwan told the Reuters news agency that those responsible "intended to destroy the economy and tourism, because the incident occurred in the heart of the tourism district".

"It was a TNT bomb... the people who did it targeted foreigners and to damage tourism and the economy," he said.

The government would set up a "war room" to coordinate the response to the blast, the Nation television channel quoted Prime Minister Prayuth Chan-ocha as saying.

Notes from the field - Maher Sattar

Not too long after the blast, the police started to cordon off the area. As I was walking away I saw one of the officers picking up what looked like little cotton pads that were soaked in blood - probably a leftover from someone trying to treat one of the wounded in the aftermath of the blast.

At the spot of the blast there was a motorcycle on the street, blown into at least two pieces. Officials in the area were looking around for more bombs - I kept hearing that more bombs had been found - there were a lot of rumours going around.

Soon, all of the press and passersby gathering in the area had to move further and further away - they were expanding the search area for more bombs - the area was not risk-free.

Chan-ocha had called an emergency meeting with high-level government officials and military officers in charge of national security in the wake of the attack.

No one has claimed responsibility for the blast.

Bangkok in shock

Al Jazeera's Wayne Hay, reporting from near the scene on Tuesday, said the Thai army chief, General Udomdej Sitabutr, said the bombing "did not match the tactics" of Muslim rebels in the country's south.

The rebels, who Thai forces have been fighting for years, have rarely launched attacks outside their ethnic Malay heartland.

"Thailand is under military rule....There have been two coups in eight years removing democratically elected governments," our correspondent said.

"There are going to be a lot of rumours over coming days and weeks and we may never know."

Our correspondent said Bangkok appeared to be "very much in shock" the morning after the attack. 

While the blast site has been cordoned off and security in the capital has been lifted, a state of emergency has not been imposed.

Al Jazeera's Veronica Pedrosa, who was at the scene shortly after the blast, said the explosion sent people "running for their lives".

"Bodies, twisted metal and debris were scattered across the street at a place popular with locals and tourists," she said.

Al Jazeera correspondent said Bangkok appeared to be "very much in shock" the morning after the attack [Reuters]

Source: Al Jazeera and agencies