A second bomb exploded beneath Sathorn bridge sending passengers and visitors running in panic.
But the explosion did not cause any injury to people.
Royal Thai Police spokesman confirmed the second bomb was a pipe bomb similar to the bomb used in Ratchaprasong.
The explosion at about 2.25 pm was near the Sathorn river pier which is the terminal for Chao Phraya river commuter boats and a short distance from the Skytrain station. It’s also a popular stop for Chinese tour groups.
Residents living in highrise buildings near the river bank reported hearing the deafening sound of explosion which they said it also shook their rooms.
It was so loud that it sent pigeons to fly away in panic, one resident said.
Manager of the Sathorn pier said the bomb, which he said might be pipe bomb, was hurled from the overhead Sathorn bridge but hit a railing of the BTS overhead pedestrian overpass and fell into Sathorn canal which connects to the Chao Phraya river.
The explosion was so powerful that it sent the water into the air for over 10 metres high.
A surveillance camera beneath Sathorn bridge also showed pedestrians running in panic as the bomb went off and splashing water into them as they were walking up the overpass.
Explosive ordnance disposal police arrived at the scene and sealed off the bridge looking for more bombs.
Forensic police also arrived to collect evidence.
Surveillance cameras on the bridge might have captured the bomb suspect.
Forensic police said they collected many small pellets which were believed to be part of the bomb.
It was not known if the second explosion was linked to the deadly bomb at Ratchaprasong or not.
Royal Thai Police Pol Or Gen Prawut Thawornsiri said the bomb was a pipe bomb similar to the pipe bomb at Ratchaprasong.
He said the thrower intended to hurl the bomb into the commuter pier but missed the target.
The place is also a place where tourists will come to board boats.
EOD police have discovered a big part of the bomb which indicated the bomb did not function fully.
Soldiers and police have now sealed off the area as they feared the perpetrator might try another attempt.
The fourth clip, taken by Bangkok Post photographer Pattarapong Chatpattarasill, shows explosive ordnance disposal officers inspecting the scene of explosion.The blast killed 20 people, including three foreigners, and injured 125.