Bombers have targeted tourists at a religious shrine in central Bangkok, killing at least 21 people and wounding 120 more, according to reports.

The damage could have been three times worse. Local police reportedly defused two bombs at the shrine and another on a train.

There have been no reports of Australian casualties.

• ‘A deafening bang. Screams. All I see is fire’
• ‘Convict Pistorius of murder’
• Sydney siege inquest: prosecutors ‘not at fault’  

Body parts were scattered across the street after the bomb exploded outside the Erawan Shrine in the downtown Chidlom district of the Thai capital.

The blast left debris all over the busy street. Photo: Getty

“It was a TNT bomb … the people who did it targeted foreigners and to damage tourism and the economy,” Thai Defence Minister Prawit Wongsuwong said.

The Department of Foreign Affairs (DFAT) said it had no information that any Australians had been killed or seriously injured in the blast.

DFAT has not upgraded its alert warning in Thailand although it is advising Australians to stay away from the blast area.

Thai police said 19 were confirmed dead, including 10 Thais, one Chinese and one Filipino citizen.

Earlier reports from local media said at least four of the dead were foreigners. 

“I can confirm it was a bomb. We can’t tell which kind yet, we are checking,” national police spokesman Lieutenant General Prawut Thavornsiri said.

Deputy national police chief Aek Angsananond said a motorcycle was involved in the blast.

Police and ambulances rushed to the scene after the bomb went off around 7:00pm (local time).

The Erawan is a popular shrine to the Hindu god Brahma but is visited by thousands of Buddhist devotees every day.

It is located on a main road through Bangkok’s commercial hub and is surrounded by three major shopping malls.

Police search for other explosives: reports

The scene after the explosion in central Bangkok. Photo: AAP

News agency Reuters reported a soldier told onlookers to move back, saying they were checking for a second bomb.

Freelance cameraman Florian Witulski in Bangkok told the ABC he had spoken to a member of the bomb squad who said two other suspected explosives had been found in the area.

He said the blast occurred at a major intersection and an area with several hotels. He said there were many burnt out motorbikes on the scene.

“It must have been a really strong explosion,” Witulski said.

There was no immediate claim of responsibility.

Police say they are preparing two diffuse the two remaining bombs at Ratchaprasong #BangkokBlast @ChannelNewsAsia pic.twitter.com/IfLsp1KBXT

— Arglit Boonyai (@ArglitBoonyai) August 17, 2015

Thai forces are fighting a low-level Muslim insurgency in the predominantly Buddhist country’s south, although those rebels have rarely launched attacks outside their ethnic Malay heartland.

The country has also been riven for a decade by intense and sometimes violent rivalry between political factions in Bangkok and elsewhere.

The army has ruled Thailand since May 2014 when it ousted an elected government after months of at-times violent anti-government protests.

– with agencies