The bomb attack at the Erawan shrine Monday evening left behind a scene of terror and shocked travellers and people who worked nearby.
"It was very loud and the explosion shook the street like a thunderbolt when I passed the scene," said Kittikorn Rachan, 50, who was at the Centre Point Hotel at the time of the explosion.
- Main story: 20 dead in city bomb horror
The explosion was caused by an improvised explosive device placed on a bench inside the Erawan shrine at the Ratchaprasong intersection.
Casualties were rescued and rushed to hospitals, in particular the nearby Police General Hospital.
The area is popular with tourists and Thais, many of whom reacted with shock at the scenes of devastation wrought by the blast.
Police said Tuesday morning 20 people died and 125 were wounded. Three foreigners were among those killed - two Chinese and a Filipino.
"It was very loud and the ground shook like an earthquake," said Charnchai Pathumsit, a hotel security guard who was waiting at the traffic lights at Ratchaprasong intersection.
"I felt like I was hit by a big rock on my right ankle and suddenly I fell with my motorbike to the ground," he said as he received treatment at Police General Hospital.
More than 50 of the injured were sent to the hospital.
Of them, more than 20 were seriously injured while the remaining 30 sustained minor injuries.
"When I opened my eyes, I saw a car engulfed in flames and everything surrounding me was a mess.
"Many people died and were injured, and many people were calling for help," said Mr Charnchai.
Adisak Itkoom, 45, a motorcycle taxi driver, heard the explosion and felt a tremor at Silom intersection.
Jittisut Somta, 28, a traditional Chinese medic at the Police General Hospital, said he was on the sixth floor of the hospital when the bomb went off.
"The explosion was so intense that the window pane in my office broke and I had to look down to the street," said Mr Jittisut.
"I felt unsafe as I come to work every day and pass that intersection," he said.
He said many of the people injured from the explosion were Chinese and it was difficult for them to communicate with hospital officials.
A large number of the injured Chinese were being treated at the Police General Hospital and Ramathibodi Hospital and both hospitals were in need of translators to help doctors speak to the injured people.
Prasert Treewichitsilp, deputy director of Chulalongkorn Hospital, said 30 injured people, including Thais and foreigners, were admitted there.
Several injured people were sent to Ramathibodi Hospital and about five were taken to Rajavithi Hospital.
A bomb disposal officer helps a team member with a protective outfit as damaged motorcycles litter the street. (Photo by Krit Promsaka na Sakolnakorn)
A police officer uses a flash light to examine damage to the fence at the Erawan Shrine after the explosion. (Photo by Kosol Nakachol)